bubble in my floor?

Help plz, I laid a laminate wood floor, and abt month later a big bubble appeared ( 2 x 5area). So i took off all the trim to see wear it needed more room to expand, found and fix. all good to go, so i thought then it came back, same spot same boards, re took the trim off and found nothing, room all around the edges for it to expand!!! Boy am i confused and frustrated!! HELP????