Problems During Sex

So Ive been with my boyfriend for going on 6 months now and up until about a month ago, having sex had never been much of a problem, aside from an extremely mild case of cervicitis. Nor has it been a problem with any of my other partners in the past. But lately Ive been completely unable to get aroused and sex is extremely painful. Anyone else with the same problems? Its not that I dont want to, I just cant and its frustrating.