Flopped a set, straight draw gets there on turn

[TBag]

170bb's deep. Villain is around 30/21/1.2 and I've been playing pretty aggresively against him, reraising in position and cbetting often.

Poker Stars - No Limit Hold'em Cash Game - $0.50/$1 Blinds - 6 Players - (LegoPoker HH Converter)

SB: $105
BB: $13.90
UTG: $107.15
MP: $112.90
CO: $186.75
<font color="black">Hero (BTN): $177.05</font>

<font color="black">Preflop:</font> Hero is dealt 9[img]/images/graemlins/heart.gif[/img] 9[img]/images/graemlins/spade.gif[/img] (6 Players)
2 folds, <font color="red">CO raises to $4</font>, <font color="red">Hero raises to $15</font>, 2 folds, CO calls $11

<font color="black">Flop:</font> ($31.50) T[img]/images/graemlins/club.gif[/img] 9[img]/images/graemlins/diamond.gif[/img] 7[img]/images/graemlins/heart.gif[/img] (2 Players)
CO checks, <font color="red">Hero bets $22</font>, CO calls $22

<font color="black">Turn:</font> ($75.50) J[img]/images/graemlins/heart.gif[/img] (2 Players)
<font color="red">CO bets $30</font>, <font color="red">Hero ?!!?!?</font>