around 21 weeks you will be growing to make room for the babs - your ligaments will be stretching which can cause some pain - it could be that - i had it x
I got them with my 2nd pregnancy from 13 weeks. Happened all the time that much so I stopped joking about going into labour as it became boring! Then when it really was happening I didnt even realise until I felt definite pain and by then it was time to go straight to hospital. I once read in a magazine that it's your womb practicing contractions so I liked to think that the more practice it had the easier the labour would be. Worked for me anyway :)