Teach me to protect - PUH-LEASE!!!

[crownjules]

What did I do wrong on this hand? Should I have check-raised on the flop? It seems this has been my luck for the past month on Party.

Party Poker 0.5/1 Hold'em (9 handed) converter

Preflop: Hero is BB with 9[img]/images/graemlins/club.gif[/img], 9[img]/images/graemlins/heart.gif[/img].
UTG calls, <font color="#666666">2 folds</font>, MP2 calls, MP3 calls, <font color="#CC3333">CO raises</font>, Button calls, <font color="#666666">1 fold</font>, Hero calls, UTG calls, MP2 calls, MP3 calls.

Flop: (12.50 SB) 7[img]/images/graemlins/club.gif[/img], 5[img]/images/graemlins/diamond.gif[/img], 9[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(6 players)</font>
<font color="#CC3333">Hero bets</font>, UTG calls, MP2 calls, MP3 calls, CO calls, Button calls.

Turn: (9.25 BB) Q[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(6 players)</font>
<font color="#CC3333">Hero bets</font>, UTG calls, MP2 calls, MP3 calls, CO folds, Button calls.

River: (14.25 BB) K[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(5 players)</font>
<font color="#CC3333">Hero bets</font>, UTG calls, <font color="#CC3333">MP2 raises</font>, MP3 folds, Button folds, Hero calls, UTG calls.

Final Pot: 20.25 BB