I have dealt with exactly what you are describing. What you are describing sounds very much like an anal fissure. I waited 6 months with the same pains you are describing, and too embaressed to seek medical attention about it, treated what I thought was hemmeroids, Finally, in so much agony, I went to my Gyno. who referred me to a Surgeon. He told me they were fissures, very common, but very painful. The reason they become chronic, it often the location. If found on the anterior wall of the rectum/anus (the back part, in front of the tailbone), it is constantly irritated and reopens with every bowel movement, thus making it difficult for it to heal.
I had a colonoscopy last week and preped the day before. I have been dealing with fissures since last summer. Because of this and some other complications, I underwent a colonoscopy to search for signs of Crohn's.
The day I preped, I was worried about the same things you are. The pain of the constant going. I will tell you, the preping did stink. My buns still hurt from sitting on the toilet for 4 hours straight:) However, since what mostly comes out is very watery (sorry if this is too explicit), it does not strain that area where the fissure is, and actually, was not that bad for me.
I will tell you what has been helping my fissure heal. ( I have done all of the non invasive procedures-stool softeners, sitz bathes, ointments, and a high fiber diet). I almost went through with a sphincterotomy(sp?). It has been super miserable. But I discovered through research the healing properties of raw, unfiltered honey. This may sound crazy, but what medicine and diet has not been able to correct in 10 months, this honey has made a tremendous difference in just a few days. On a scale of pain, often I was at a 7 or 8, and after a BM it was painful for the rest of the day. Now, I put the raw honey on the fissure, and my pain level, at most is at 2. It is amazing. I think with a little more time, it will heal completely. I think you may be surprised by the results if you give it a try. I was. You can typically find raw, unfiltered honey in the organic section of your supermarket or at any organic, health food shop.
I wish you luck. Hope things go well for you.
I have had the same problem for along time also the itching can get bad.My doc told me that it was just hemroids and they can pop sometimes and that can make you feel really bad for awhile and you can bleed for 1 to 2 days also the bleeding is not alot but its enough to make you scared sometimes.I think the best thing to help with the burning is A&D cream the stuff you use on babies when they get a rash sometimes that helps are dont wipe with t.p. just use a spray bottle with cold water.I wish you well and dont worrie Im sure its just hemroids.