Personally i havent had any pain issues with orgasm, but have had frequent 'sensation/feeling' issues in that sometimes i cant really feel alot down there. Again Personally i have found it can be the level of medication i have needed that day and the type of medication i needed. For me i can also link this to trouble peeing and pooping in that the message(from brain) to muscles either isnt getting there or your muscles are confused and just arent doing what they should when your telling them to.
(And before anyone says it from the sensation side of things i have been fully tested for multiple sclerosis and that is definitely not the case for me.)