I'm a nutritionist. Make sure your eating a high fiber diet....i.e. whole wheat bread, oatmeal, brown rice, cold cereals that are high in fiber and low in sugar, etc. Find out if your lactose intelorate. The best way to do is this to cut out all forms of dairy for about 10 days and see if it stops. (If you must drink milk during this time, drink soy milk). If you have already seen a regular doctor and he can't help you, try a holistic dr. Have him test you for yeast (Is it possible that this started after taking an antibiotic?). Good luck!
You should go see a doctor about that b/c excessive diarrhea can make you dehydrated. And being dehydrated can bring about a whole lot of symptoms on its own.