Anything i eat is causing bloody diarrhea and bloating. started after some antibiotics. tested for c.diff neg few times. i started having fissures because of diarrhea. what to do?

You need to see GI: this could be intestinal inflammation. You need to see a gastrologist to clarify whether you could have something like inflammatory bowel disease. This is something you need to discuss with your physician.

Other infection: There are diff tests for C. Diff. You may be being checked on a test with a high "False Neg" rate. Make sure the test is being run by a quality lab and & diff test methods have been used. Regardless, mult false neg would be odd. Why were you on abx? How long? Were you on probiotics? This needs to be looked into and other infections or inflammatory bowel disease ruled out. See a GI doc ASAP.

Bloody stools : Antibiotics can cause diarrhea & C diff infection, the blood could be from the anal fissures, other bacterial infections can cause bloody stool, you need to do stool cultures to find the actual cause of your bloody stools to get the proper treatment, at the mean time avoid dairy products and eat light diet, soup, crackers, plain rice, bread , apple, Bananas. Jello, tea & stay hydrated. Good luck

Diarrhea: Antibiotics can cause diarrhea. As you mentioned c.diff test is negative few times. But, what is the reason you are taking antibiotics? Now you developed anal fissures, could be due to prolonged diarrhea or any other cause. I think you should consult Gastroenterologist ASAP to rule out inflammatory bowel disease such as Crohn's disease etc or other causes. You may need different treatment.