J-pouch and masturbation/sex and pelvic pain

I don't know of any restrictions in regards to sex or masturbating with a j-pouch (for males at least).  Definitely let your doctor know about this though.  That's what they are there for, and don't be afraid to ask.  They hear this stuff more often than you think.

There should be no issues. It may be due to scaring, like maybe something is being restricted because of scar tissue. I would definitely suggest talking to your doctor.

If you really haven't been masturbating for a time it could also just take some time to get use to it.

Did you have a open surgery or was it laproscopic? Having issues with errectile function is a possibility that I was warned about before surgery, although I was also told that it had never been an issue at my surgeons office.

I hope that is helpful.