Had stomach waves of cramps, migraine, diarrhoea (Which turned bloody for a few days then returned to 'normal' diarrhoea) a few weeks ago. I am now slowly getting back on track but do still have to be careful what I eat and bum still feels weird (Like a bubble has got stuck). Stool sample came back normal and I am not in pain but am worried this was a first real flare up of ulcerative colitis or chrones or even worse anal cancer. Does it suddenly come on like this and can go away on its own? My doctor thinks I may have had food poisoning originally which can cause blood in stools.