Alyssa,
I go thru periods of a few weeks where I feel like I am getting better. Only for the pain to return again. I haven't figured out what or if I have done anything different when I have these periods. Yes it is very frustrating. Especially when you consider all the marvels of modern medicine yet they can't cure us?
I would get an MRI done to rule out anything nasty in the pelvis. Also get your spine done as well, those nerves in particular the sacral nerves can have an effect on the rectum.
I still believe though it's something to do with all our surgeries in the area. It seems to be a common factor for a lot of us with chronic pain in the rectum.