Dude, you really need to stop fearing monsters (just like in your other post in the SH forum when you had JJ and cbet flop and checked the turn on a draw heavy board for "pot control"). Sure it's possible he might have a set, but that does not mean you should check this flop. Also a nit is not the best player to induce a bluff from. The way to counter this type of player is not to turn into a scared nit postflop when you don't flop the nuts, but to loosen up and punish these limpers by raising with a wide range and not letting them play comfortably. If your opponents know that your range for the given pf action is AA/KK/QQ, then you become horribly exploitable, and the solution is not to go straight into pot-control mode when you don't flop a set. And if you know his range is only small pocket pairs, then HE becomes horribly exploitable, so use this to your advantage.

I am being straight up with you here, because at higher limits this type of scared play will get you run over by the better players.