Re: supplement, diet, and diarrhea question--need help soon!
Jessers11581, you mentioned that this began suddenly about 4 weeks ago. Diarrhea is common with IBS, of course, but IBS doesn't just pop up overnight. You mentioned eating many sweets during Christmas and a possible yeast connection, but this presumably would have at least subsided somewhat since then if there was a connection.
My best advice would be for you to rule out (or rule in) a parasitic infection of some sort, and then go from there. Such infections can produce sudden symptoms, as you would guess. Finding helminths (worms) in a sample is not too tough, and many local labs your doctor may use could succeed in that. But a protozoal or bacterial infection is much more difficult to clinically diagnose, and only a few labs do it well, the ones which specialize in it. I assume you're in the U.S. -- if so, three reputable gastrointestinal labs are Great Smokies in North Carolina, Great Plains in Kansas, and Parasitology Center in Arizona (links below). Each of these labs should have a physician referral service for local docs in your area who are familiar with their paperwork and already have accounts opened with the labs. The reason I say this is, the likelihood of your doc saying "I'll just the local lab I always use," and then getting a false negative lab result, is very real, and quite common. Something to consider. Good luck!
http://www.greatplainslaboratory.com/home.htm
http://www.gsdl.com/home/
http://www.parasitetesting.com/