Well, I would say that you either need to fold or push here,. There are some players that've been known to checkraise with nothing (I've done it) and you can't afford to give any free cards to overcards. Just calling is terrible because it allows an aggressive player to take you off a winning hand if any number of scare cards come on turn (whether they have them or not). Without a read that this player is very active and capable of c'ring with air, it may be best to save your chips for occasions where you can seize the betting impetus.