The ole' 4-bet, fold to a 5-bet

[Ryno]

Commerce 40/80

Button is relatively unknown to me, but has been quiet. BB is a regular who is sorta tight, not very aggressive, the kind of guy you raise the turn when you have 2pair+ and he reliably pays you off with his top pair, but you get no more than 3BB from him ever if that's all he has.

I open with KK in MP. Button coldcalls, BB calls. 3 players.

Flop is AK2 rainbow. Check; I bet; call, BB checkraises; I call; Button calls.

Turn 2. The BB hesitates and checks. I bet. Button calls. BB checkraises again.

The deuce must have helped him. I get it in my head he has A2. But I wouldn't mind another bet from the button so I call. Button folds [img]/images/graemlins/frown.gif[/img]

River Jack. He bets, I raise, he 3bets. I am still on track with the A2 read. There is no way possible he called the BB with AA. I 4bet. He 5bets in the most spazzy way possible, like he cut 4 stacks but they are 6chips, 2chips, 3chips, and 5chips high.

Am I allowed to fold?