NL25 KK

[HighCardSeven]

PokerStars No-Limit Hold'em, $0.25 BB (5 handed) Poker Stars Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

MP ($26.85)
Button ($13.90)
SB ($16)
BB ($24.30)
Hero ($29)

Preflop: Hero is UTG with K[img]/images/graemlins/spade.gif[/img], K[img]/images/graemlins/club.gif[/img].
<font color="#CC3333">Hero raises to $1</font>, <font color="#CC3333">MP raises to $3</font>, <font color="#666666">3 folds</font>, <font color="#CC3333">Hero raises to $14</font>, MP calls $11.

Flop: ($28.35) 5[img]/images/graemlins/heart.gif[/img], 9[img]/images/graemlins/heart.gif[/img], A[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
Hero ???

MP was 45/28 after 29 hands. I cant believe that he calls my 4bet preflop. Without an ace I would push every flop. But the flop scared me because of the Ace and I think if I push only better hands will call. What should I do? Check/Call to induce a bluff? Check/fold is to weak, right? Or just push allin without a second thought?