I have had the same problem since 2004 and been to about 5 different physicians who cannot pinpoint the problem. It is like a ring of scar tissue exists right up inside my hole and it is sometimes as though the hole is swollen shut from the inside.
There is never a feeling of completion after BM. I used to go 3x per day but there was never a burning, discomfort, cramping feeling afterwards as there has been the last few years.
There is also a feeling of trapped gas and reflux, so much that often I burp up chunks of food. This may be unrelated but it is often worse after sex/ejaculation, believe it or not.
Sex seems to make a difference. While there is no pain/discomfort during, there does seem to be some sort of internal congestion that goes right from under the ribcage down thru the perineum to rectal area that happens almost every time.
Earlier in the decade, I had (stupidly) developed a practise of "holding off" as long as I could and was sometimes erect for several hours before release. While I am certain this has caused these problems, the doctors I have seen are all skeptical.