I would say keep up your diet and try exercising regularly (30 min everyday, 15 when you're pressed for time as something is always better than nothing). Have you tried glycolax? I heard that works a bit differently than other things meant to stop constipation by cleaning the walls of the intestine as well. For the prolapse, you may have to see a colorectal surgeon to have that fixed. The white growth on your inner cheeks sounds a bit weird. That might be a fungus or something? Thrush/candida? What did your doctor have to say about that? Also, did he give you a reason for why the proctitis could be there? (there are some possible causes here:http://digestive.niddk.nih.gov/ddiseases/pubs/proctitis/) Shouldn't he at least give you some anti-inflammatory meds?
In short, I'd recommend: water, glycolax, keeping up diet, starting exercise, seeing colorectal surgeon about prolapse, seeing if the doctor can do anything about the proctitis. Sorry I couldn't be of more help! If nothing else works, you could also try looking into/researching FMTs (Fecal Microbiota Transplant), some people have had good results from that procedure, though it's not very accessible (but you could always DIY). Best of luck! :)