Did I Overplay my over pair?

SB is here is unknown
Button is 36%/0/1.0/14

Party Poker 2/4 Hold'em (9 handed) FTR converter on zerodivide.cx

Preflop: Hero is CO with Q[img]/images/graemlins/diamond.gif[/img], Q[img]/images/graemlins/club.gif[/img].
<font color="#666666">5 folds</font>, <font color="#CC3333">Hero raises</font>, Button calls, <font color="#CC3333">SB 3-bets</font>, <font color="#666666">1 fold</font>, <font color="#CC3333">Hero caps</font>, Button calls, SB calls.

Flop: (13 SB) 5[img]/images/graemlins/diamond.gif[/img], 4[img]/images/graemlins/heart.gif[/img], 9[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">SB bets</font>, <font color="#CC3333">Hero raises</font>, <font color="#CC3333">Button 3-bets</font>, <font color="#CC3333">SB caps</font>, Hero calls, Button calls.

Turn: (12.50 BB) 4[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">SB bets</font>, Hero calls, Button calls.

River: (15.50 BB) 6[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">SB bets</font>, Hero calls, Button calls.

Final Pot: 18.50 BB

Should I have folded the turn here? the warning sirens were going off that SB probably had me beat, and that button may have hit a set. Should I just fold or was I right to call down with the over pair? and if I should have folded, WHEN should have I? When he capped the flop?