Can Constipation Be Confused with Diverticulitis

My fiance has had very severe abdominal pain in his left side for the past two weeks. At first he just seemed to be constipated. Hes always had an enlarged colon, so he thought maybe something was wrong, hes been in and out of two different hospitals atleast 5 different times and the doctors keep saying its constipation, its not. One would think that after having an Enima almost every day for the past 10 days, there wouldn't be any stool to flush out. I had heard of something called Diverticulitis, and Im wondering if thats what it could be. He has all the symptoms, very bad gas, vomitting, loss of appetite, abdominal pain in the lower left side. Its so bad he cannot move and he refuses to eat. Every time hes gone to the hospital, they've done X-rays and they've not said anything about it, and I believe they've also done a blood test or two, but Im not sure if it was a CBC or not. I know Diverticulitis can be found through X-rays, CT Scans, and through a colonoscopy. We've made an appointment with a Doctor who specializes in Gastroenterology, but its not until the beginning of September and Im afraid somethings going to happen, this sounds like something far worse than what the doctors are telling me. I dont know what to do anymore, everyone I take him to says its Constipation and I know it cant be, it just cant.