Stomach problems for over 3 months now...any ideas?

I am a 35 year old woman who has Lupus and has had daily diahrea for at least 3 months now. I have 3-5 bouts of it a day without fail and it is getting worse. It wakes me every morning and I am steadily loosing weight. I have had a colonoscopy which has revealed only hemmroids and a CT scan of my abdomen and pelvis which was fine. I have been prescribed Nexium and Librax which have done nothing for me. I was also given antibiotics for E. Coli and that did nothing either. I have had stool samples and bloodwork all have which been OK, I think. In addition to the diahrea, I also have bloating and severe loss of appetite. I am really at a loss of what this could be and I am not happy with the care that my current GI doctor is giving me so I am switching but was wondering if anyone else had any ideas.