The doctor that did your colonoscopy should have told you right afterwards if you had diverticulitis. Call his office and request an immediate copy of his results. If they can't or won't do that, talk to his nurse to find out. There should be no reason to take antibiotics unless you need them. They can also cause problems with your bowel movements.
After my colonoscopy, my doctor told me his findings and while he didn't see any signs of the adhesions, he did find some internal hemoirhoids (which I already knew about). Please find out directly from him or his nurse as soon as possible. Tell them what your other doctor is 'assuming'.
Hang in there!
kcmo rose