[TStoneMBD]

i think you need to bet the flop. if SB checkraises you then just give up, but you shouldnt give a free card and betting gives you more information than checking for sure.

after the button bets the river i think you have enough of a hand to call. there are alot of Qx hands that will peel the turn and he almost certainly doesnt have a king after checking the flop. hopefully he just doesnt have a jack or tripped up with a ten which is also fairly unlikely from the flop action.