Hi.
Thanks for your query.
Noted the history and understood your concerns.
Surgery for rectal mucosal prolapse and piles/hemorrhoids by infrared 18 days ago should have been absolutely painless by this time.
The pain on passing bowel movements indicates one of the following reasons:
Infection locally.
Hematoma that did not resolve.
Involvement of skin in the procedure which is sensitive and causes pain on passing BM.
This can be diagnosed by the following:
Per-rectal digital examination.
Ano-proctoscopy and
colonoscopy at a later date when the pain allows.
MRI of the area can show any hidden inflammation, pus or so.
If needed a small procedure may be needed if there is a collection.
Take painkiller with anti-inflammatory property like
Ibuprofen.
Laxatives.
Sitz bath in a tub with warm water.
If required take a
second opinion of another SUrgeon for proper diagnosis and proper management.