hello,
There are a couple of possibilities. One is
inflammatory bowel disease. This is usually accompanied by
diarrhea, which is not one of your complaints. However, the initial problem can be
constipation or nausea. Your gastroenterologist should have considered this and tested for it. If he/she didn't, ask again if this could be the problem. You will get a definite answer with the proper imaging and
endoscopy. If the site of disease is hard to reach with an endoscope, you can find a center that offers a special test where you swallow a tiny camera that takes pictures along the entire length of the intestine.
Celiac disease is another possibility, but it sounds unlikely because diarrhea is the usual symptom. You can rule this out with diet: eliminate all wheat and barley, just eat corn or rice for a week or so. You have to read labels very carefully, because a lot of things you would never suspect (like soup) can contain wheat flour.
Finally, your original infection might have been bacterial rather than viral. In this case, you might have a persistent intestinal infection, or bacterial overgrowth (too much bacteria, or bacteria in the wrong part of the gut). This is easy to diagnose and treat, but most gastroenterologists either don't know about these or fail to consider them as possibilities. The treatment is antibiotics, particularly the non-absorbable (approved for traveller's diarrhea, but not for bacterial overgrowth, so treatment is ungodly expensive).
The diagnosis for an overgrowth or infection without overt symptoms of diarrhea is either a
breath test or endoscopic aspiration of intestinal contents. The breath test will pick up infections far below the stomach; the endoscope will only detect the most serious infections that involve the upper intestine just after the stomach. The breath test involves swallowing a non-digestible, non-absorbable
carbohydrate and blowing into a bag at regular intervals. The amount and types of gases you exhale are measured to determine if you have excessive bacteria.Be persistent about getting this checked out. Don't take "we can't find anything wrong" as an answer. There is always an answer, and you may have to changes doctors to get the right answer.If you are afraid about what is happening - or might happen - get some counseling. Illness is bad enough, but when it doesn't go away, sometimes you need help coping with it.
thank you.