Link to original: http://sphynxcatvp.nocturna.org/health/sc-gi-diseases.html
Sometimes a digestive complaint is more long term or chronic, a result of a disease or what's often referred to as a "functional disorder". This article covers some of the various diseases processes associated with common digestive complaints.
This was originally contained within my original "why can't I eat anything" - I split this portion out (to make it easier on translators who only translate part of a page) and expanded it with more information, and updated the reference links.
Celiac Disease / Celiac Sprue / Gluten-Sensitive Enteropathy
For Celiac patients, gluten actually causes an abnormal immune system reaction, which destroys the "villi" in the small intestine. This, in turn, makes it harder for the body to absorb nutrients, and eventually generates a serious malnutrition situation - the patient becomes malnourished, no matter how much food they eat. Symptoms may include abdominal bloating and pain, chronic diarrhea, constipation, vomiting, and weight loss. Celiac is considered to be an autoimmune disease due to the destruction of the villi, and tends to run in families.
Crohn's Disease / Ileitis / Enteritis
Crohn's Disease causes inflammation of any location in the digestive tract - it's not limited to specific sections, like Celiac would be. It most commonly affects the "ileum", or lower part of the small intestine. The inflammatory process causes pain and will frequently cause diarrhea. Because the symptoms are very similar to other intestinal disorders such as irritable bowel syndrome, it can be difficult to diagnose - in fact, some patients may go twenty years before an accurate diagnosis is finally made, and end up with one or more surgeries to remove the parts of the intestine that are chronically inflammed.
Chronic Constipation / Fecal Impaction
A fecal impaction is a large mass of dry, hard stool that can develop in the rectum due to chronic constipation. Sudden, watery diarrhea in someone who has chronic constipation is usually an indication of a fecal impaction (it's watery because that's really all that can get past the blockage - solids get stuck and make the blockage bigger, hence the need to get it taken care of ASAP.) If the problem is not taken care of, it can lead to death or ulceration of the affected tissues. This tends to happen on a diet high in meat products and very lilttle vegetable, fruit or fiber. You can prevent fecal impactions by having plenty of fiber, fruits and vegetables (preferrably raw) on a daily basis. (Or you can also add extra magnesium to your diet - magnesium is a natural laxitive in large enough doses.)
Common symptoms can include sudden pain after eating or drinking either certain foods, or more typically any fatty or greasy foods such as meat, french fries, etc., with the pain lasting up to several hours. Other symptoms can include nausea and bloating, fever, yellowish color to the skin (Jaundice). If the gallbladder is blocked by gallstones for a significant period of time, severepossibly fataldamage or infections affecting the gallbladder, liver, or pancreas can occur. Warning signs of a serious problem are fever, jaundice (yellowing of the skin and eyes), and persistent pain.
A kidney stone is a hard mass developed from crystals that separate from the urine and build up on the inner surfaces of the kidney. These may be caused by chemicals within the body or as a byproduct of a urinary tract infection. Typically, a person feels a sharp, cramping pain in the back and side in the area of the kidney or in the lower abdomen, and often described as "The Worst Pain Ever". Sometimes nausea and vomiting occur. Later, pain may spread to the groin. If fever and chills accompany any of these symptoms, an infection may be present; in this case, you should contact a doctor immediately.
Irritable Bowel Syndrome & Ulcerative Colitis
Irritable bowel syndrome (IBS), one form of which is Ulcerative Colitis, is a disorder that interferes with the normal functions of the large intestine (colon). It is characterized by a group of symptoms - crampy abdominal pain, bloating, constipation, and diarrhea. Abdominal pain or discomfort in association with bowel dysfunction is the main symptom. Symptoms may vary from person to person; some people have constipation (hard, difficult-to-pass, or infrequent bowel movements); others have diarrhea (frequent loose stools, often with a frequent and urgent need to move the bowels); and still others experience alternating constipation and diarrhea. Some people experience bloating, which is gas building up in the intestines and causing the feeling of pressure inside the abdomen. Patients with colitis often have diarrhea as well as the need to use the bathroom more frequently than most people.
Most people with diverticulitis do not have any discomfort or symptoms. However, symptoms may include mild cramps, bloating, and constipation. Other diseases such as irritable bowel syndrome (IBS) and stomach ulcers cause similar problems, so these symptoms do not always mean a person has diverticulitis. You should visit your doctor if you have these troubling symptoms. The most common symptom of diverticulitis is abdominal pain. The most common sign is tenderness around the left side of the lower abdomen. If infection is the cause, fever, nausea, vomiting, chills, cramping, and constipation may occur as well. The severity of symptoms depends on the extent of the infection and complications.
Malabsorption (Various Types)
Malabsorption can result from a broad spectrum of diseases. Typically, malabsorption can be the failure to absorb specific sugars, fats, proteins, or vitamins, or it can be a general malabsorption of food. Diarrhea, bloating or cramping, failure to thrive, frequent bulky stools, muscle wasting, and a distended abdomen may accompany malabsorption. Malabsorption can affect growth and development, or it can lead to specific illnesses. Some of the causes of malabsorption include (all links here are from the National Institute of Health) but are not limited to:
(References are interspersed through the article)