What Causes Ischemic Colitis With Blood Discharge In A CIDP Patient?

I have CIDP. I am currently in remission and have regained the ability to lift my feet but still have much numbness in my feet and hands along with a tuning fork sensation. I also have a difficulty with bowel issues, extreme pain, taking an hour or longer to finish, going from a constipated stool to watery diarhea, and I am in intense, gut wrenching pain. I have been in the hosp two time, each time ten days, for passing blood. First time it was ischemic colitis, second time undiagnosed but each time I ended up with nothing passing but blood. I have had an endo and colonoscopy. Nothing showing and I have had extensive testing as I also presented with B12 deficiency, unknown why. None of the regular possibilities, not a vegan nor was it due to celiac or gastro issues, etc. My neuro ran extensive testing. I am stumped, my gastro Dr. is just like oh well and meanwhile, I am in more pain than I can relay. This happens an average of twice a week and more often than not I vomit at the same time, so I have a hard time maintaining weight. History, I lost both breasts to cancer 2004, it was very early stage but aggressive and they did mastectomies for the grade and family history. Also, I was misdx with MS for four years and gave myself shots of betaseron. When the CIDP started really getting bad, it went fairly quickly. Thx.