About stomachs problem?

My brother got diagnoised with diverticulosis a couple of months ago by mistake and the doctor tells him dont worry just eat a high fiber diet now v8 does help him move his bowels but for months now the consistancy in his stool has changed sometimes being skinny he says also he has very bad stomatch pain all the time the doctor says that it is acid reflux but the medication they gave him protonix dosent help so now he has nausea mixed with this and he gets constipated often we wanted to have a follow up of the ct scan for his belly done agin to make sure the diverticulosis didnt turn into diverticulitis but they said go to the emergency and see what they say what the hell...the symptoms are constipation on and off but will last three days,stool change thin stool sometimes mooshy,nausea before or after eating, loss of appetite sometimes, lost 30 pounds in 2 months,pain in abdomen,sharp pain in rectum and he said it feels like his hole is swollen what could this be?