First, I have to say I am glad I re-read your title. At first I read it wrong and thought it said "I can't bowel anymore." I was going to post a recommendation to see a doctor soon!

I am sorry about this and how you are feeling. I am not a bowler but is there some way that you can improvise? (Like AMN's picture. lol). Certainly you could bowl from a chair, right? Or maybe team up with another bowler and take turns? If this isn't possible, what other ways can you go with everyone and still enjoy yourself. I think that is the most important part, making things work so that you still enjoy yourself.