TPGK, 5 opponents, flush draw on flop

[calidris]

Poker Stars
Limit Holdem Ring game
Limit: $0.25/$0.5
9 players
Converter

Pre-flop: (9 players) Hero is Button with K[img]/images/graemlins/heart.gif[/img] Q[img]/images/graemlins/spade.gif[/img]
UTG calls, 2 folds, MP2 (poster) checks, MP3 calls, CO calls, <font color="#cc0000">Hero raises</font>, SB calls, BB calls, UTG calls, MP2 folds, MP3 calls, CO calls.

Flop: 7[img]/images/graemlins/club.gif[/img] K[img]/images/graemlins/club.gif[/img] 3[img]/images/graemlins/heart.gif[/img] (13SB, 6 players)
<font color="#cc0000">SB bets</font>, BB folds, UTG calls, MP3 calls, CO calls, Hero ?

This flop i suddenly got confused and didn't really know what to do. Normally I'd raise here since I raised PF but against 5 opponents? Raising won't limit the field since they all called one bet already and I'm last to act. If i'd been number two I'd raise in a heart beat.

Raising could give me an opportunity to win it with a turn bet or get a free card, but if a 3-flush comes up I'm getting really nervous against 5 opponents. Suggestions?