Is the tooth pain a throbbing pain? Or is it sensitive to cold, hot, when does it most hurt, all the time? What kind of filling was it. Sorry just questions I am use to asking, hard to say without x-ray to determine weather or not you need a Root Canal. They usually try not to do RCT in first trimester, but your OB and dentist should tell you weather or not Lovenox would interfer. I do not think so, but they might want to wait till second trimester, but depends on severity.