NL50 SH - two pair on turn

[insertnickname]

What do I do here?
Haven't played a lot against this player, so hardly any reads

Party Poker, $0.25/$0.50 NL Hold'em Cash Game, 6 Players
LegoPoker Hand History Converter

UTG: $42.63
MP: $52.23
CO: $39.42
BTN: $49.25
Hero (SB): $56.35
BB: $60.97

Pre-Flop: 9[img]/images/graemlins/heart.gif[/img] Q[img]/images/graemlins/heart.gif[/img] dealt to Hero (SB)
UTG calls $0.50, MP folds, CO calls $0.50, BTN folds, Hero calls $0.25, BB checks

Flop: ($2) Q[img]/images/graemlins/club.gif[/img] T[img]/images/graemlins/diamond.gif[/img] 3[img]/images/graemlins/club.gif[/img] (4 Players)
<font color="red">Hero bets $2</font>, 2 folds, CO calls $2

Turn: ($6) 9[img]/images/graemlins/diamond.gif[/img] (2 Players)
<font color="red">Hero bets $4</font>, <font color="red">CO raises to $12.50</font>, Hero ?