A related discussion,
Diarrhea over a week was started.
Sometimes a yeast overgrowth in the gut can cause by diarrhea. Overuse of antibiotics and steriodal drugs can affect the balance of good microflora in the gut. I had lots of problems with this.
There is a very good probiotic on the market. It's called VSL 3. It contains 450 billion lactic acid yogurt bacteria. It's a powder that you mix with water. It's expensive though. You should try a good probiotic bacteria. That can help to restore your microflora. There are a lot of different probiotic supplements on the market that you can get in a health food store.
I'm also taking a supplement call GastroCort by Allergy Research Group. It helped me a lot. It takes a while to get the microflora back in balance.
There are a few good books on the market that deal with yeast overgrowth and the effect it can have on you.
I feel your pain with the speratic diarrhea. I have had diarrhea for the past 6 years. I have kept a journal of what I eat every day for 3 months and went to see a doctor. I have had a colonoscopy and they told me that my intestines were inflammed. They suggested to change my diet and add fiber. I did that and it only made it worse. I had severe pains no matter how much fiber I added. I would suggest to see another doctor for more advice. I am still searching for a diagnosis at the most. I feel your pain of not knowing what it is that is causing the diarrhea.
You should have a Colonoscopy to check for Crohn's disease. A non life-threatening condition of the intestines.
Yes, I have been tested for everything under the sun (or so I'm told). Including parasites. Nothing has turned up. That's why it is so frustrating for me. I also forgot to mention that I have a cold nodule on my thyroid that I have been trying to get removed. Whether that has anything to do with the diarrhea, I don't know. The other thing that is so mysterious is that I do not lose weight, you'd think that losing everything I eat, I'd be skin and bones! Not in my case.
Have you been worked up for your diarrhea at any time during all those 15 years? Sounds like you could use to have a few tests done, including a colonoscopy, stool fat, and stool analysis for ova & parasites. Some allergy testing might be a good idea as well. There are any number of things that could be causing your symptoms, but in any case this does not sound normal.