FT Hand Sanity Check

[NoahSD]

This is from the FT of a 20/180. I was very aggressive on the bubble and the FT bubble, and villain's been to my left for a while. He c/red my c-bets twice I think, so I'm pretty sure his flop bet is weak.

PokerStars Tournament, Big Blind is t1200 with t75 antes (9 handed) Converter on pregopoker.com

UTG (t25245)
UTG+1 (t59548)
MP1 (t14482)
MP2 (t14972)
MP3 (t22304)
CO (t28750)
Hero (t35857)
SB (t45537)
BB (t23305)

Preflop: Hero is in Button with 6[img]/images/graemlins/spade.gif[/img] 7[img]/images/graemlins/heart.gif[/img]
<font color="gray">UTG folds</font>, <font color="gray">UTG+1 folds</font>, <font color="gray">MP1 folds</font>, <font color="gray">MP2 folds</font>, <font color="gray">MP3 folds</font>, <font color="gray">CO folds</font>, <font color="red">Hero raises to t3200</font>, SB calls t2600, <font color="gray">BB folds</font>

Flop: (t8275) Q[img]/images/graemlins/spade.gif[/img] 4[img]/images/graemlins/spade.gif[/img] T[img]/images/graemlins/club.gif[/img] (2 players)
<font color="red">SB bets t3600</font>, <font color="red">Hero raises to t9000</font>, SB calls t5400

Turn: (t26275) 6[img]/images/graemlins/heart.gif[/img] (2 players)
SB checks, Hero checks

River: (t26275) 4[img]/images/graemlins/heart.gif[/img] (2 players)
SB checks, Hero ????

What do I put him on when he calls the flop bet and then tries to check it down?