What Causes Sudden Rise In BP Level,severe Diarrhea And Blood In Stool?

I been having sever cramps in left lower quad which activates a quick massive increase with blood pressure where i become very ill and have passed out and then vomit and have explosive diarrhea with blood in stool for a couple of days. I have had coloscopy done yearly and everything clear. My symptoms come on fast without warning and go away just as fast. I have been hospitalized for 2 weeks and all test are neg. I feel this is very serious because I feel that my body wants to shut down.