Majorly painful shooting cramp like pains in my bum :(?

Okay, so when i was a baby my bowel collapsed and i had to have a major life threatening operation to correct it, but ever since i can remember, every once in a while i get unbearable shooting, cramp like pains in my rectum, it only lasts about 5 seconds and feels a little tender afterwards. i have never really worried about it as it doesn't happen all that often, but i am now 11 weeks pregnant and a bit of a worrier and would like to find out what could be causing it and if it could be harming my baby.