ulceritis colitis or diverticulitis

hi im trying to figure things out. Two years ago i was dianosed with ulceritis colitis.I had insurance at the time but i know longer do, recently i had a major flare up i went to several hospitals that did major test and put me back on meds but they didnt help this time my husband look me to a charity hospital they admitted me i was scheduled for a upper and lower gi monday morning sunday they came in found out i didnt have a goldcard nor insurance so they discharged me, but on the discharge papers it says diverticulis and all this hospital did was cat scan and blood so my questions is how can u tell what i have through a cat scan.?Let me tell you some of my symptoms severe adominal (abdominal) pain on the left side vomiting neasea bodyaches sometimes i have blood in my stools with pus sometimes i have alot of diarrea (diarrhea) especially after i eat but sometimes my stomach cramps like its in knots.I dont have insurance so i cant go to the doc to know the truth and could the doc that tested me two years ago be wrong ?So could you give me your oppintion pls .