Out of position with a set, flush on the flop

[Nicok7]

READS: Vilain is a loose donk but I have not seen him make big bluffs so far.

Party Poker No-Limit Hold'em, $ Hero (6 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

UTG ($734.95)
MP ($764.79)
CO ($172.55)
Button ($777.19)
SB ($209.78)
Hero ($495)

Preflop: Hero is BB with 5[img]/images/graemlins/club.gif[/img], 5[img]/images/graemlins/diamond.gif[/img]. SB posts a blind of $3.
<font color="#666666">2 folds</font>, CO calls $6, <font color="#CC3333">Button raises to $26</font>, <font color="#666666">1 fold</font>, Hero calls $20, CO calls $20.

Flop: ($81) K[img]/images/graemlins/spade.gif[/img], Q[img]/images/graemlins/spade.gif[/img], 5[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">Hero bets $100</font>, CO folds, Button calls $100.

Turn: ($281) 7[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(2 players)</font>
Hero ?


Basically I can't put him on a draw very often and if he was he'd check behing on the turn. His call on the flop really worried me and If I fire another barell that s me all in.

I opted for a check on the turnm with the intention of folding if he bets big on the turn, or to check call the river if he checks behind on the turn and a blank comes.