Diarrhea for 4 weeks

I have had watery diarrhea for 4 weeks, been on 3 different antibiotics, stool cultures done, blood work done, and still have not found the problem, losing weight. The diarrhea went from a brown color to now it is a yellowish in color.
I have developed a pain in my lower left side.

[mammo]

Below are two excellent sites to address your issues and arm yourself to speak with your doctor.  Antibiotics themselves can also cause diarrhea, and I hope you are seeing a Gastroenterologist for this, and not your GP.

http://www.bm-bowel-movement.org/bm-colors/yellow-bowel-movements.html

http://www.associatedcontent.com/article/632361/left_side_stomach_pain_.html?cat=5

Take care...