Unfortunately, your flop bet was too weak, giving odds to chase, regardless of whether they are fish or not. At least a 1/2 pot bet is necessary here, to at least give us the information we want, also if they are fish, we want to pump the pot to maximize our winnings. Unfortunately your set gives QT a straight, a hand that many fish will play. I don't know what to tell you to do from here. If you reraise, you will at least find out whether he caught his straight or not. You made a mistake on the flop, and it might have cost you dearly....