I've never ever heard of 'stress related proctitis', I think you are being fobbed off.
I used to suffer with hemmies for years and they do cause a burning sensation and mega pain! I got a bad nfectin from tearing on my first child that didn't hurt as much as the stranglated piles! So you doctor is talking crap saying they don't hurt. But f it was piles, you can see them and feel them if they are external and feel them wth an inserted finger f internal, they also bleed.
I also have severe Proctitis, and funny enough the piles stopped bothering me when I got UP but I'd say that the Pentasa suppositories help me out.
With proctitis, you bleed and have mucus a lot, urgency, a feeling like you still need to go more when sitting on the lol and some pain, but I would never call it burning pain, more a throbbing dull pain in your rectum, and some left side pain.
Personally, i don't think you have either things, as you don't have any bleeding which is a big symptom of both.
Not to be to intrusive but how far up is the pain? If it's just the outside, could it be an allergy to toilet paper? If it's higher up, you need to demand a scope to investigate what's going good on.