Mystery Diarrhea

Hello all -  Just wondering if anyone has any ideas as to what might be going on with me!  

First off, I had a lap band placed last July - and I've lost over 130 lbs.  Last April I started having lots of stomach cramps, diarrhea often mixed with blood or mucousy stool.  The doctor treated me as a bad stomach bug at first, and just gave me Lomotil to slow things down until my body could get rid of it.  When that didn't help, I was put on Flagyl, which instantly cured me.  The problem was, once I came off the Flagyl, the diarrhea came back!  I was then treated with a double dose of Flagyl, again the symptoms turned off, then came right back when off of the Flagyl!

I have since seen a Gastroenterolgist, who continues to treat me with Flagyl while he tries other things such as Lialda and Canasa to treat me for IBD.  Problem is that Flagyl seems to be the only thing that my body responds to!!!  Every time I go off the Flagyl, the symptoms come back despite the other medications.  I had a colonoscopy which was inconclusive... It showed that there was some definate inflammation but not enough to conclude whether it could be Chrons or Ulcerative Colitis.  

My lap band doc's office have said it has nothing to do with the lap band.  All my stool cultures also came back negative.  I have never had any nausea/change in appetite/vomiting... it's all the other end.  

One other thought I had was that it is possible I may have eaten a rotten egg sometime before these symtoms (symptoms) started.  I have just thought of this tonight so I have not run that by any of my docs... But if any of you guys have some ideas of what might be going on or what might help me, please share!!!