50NL Ace-high flush, 3 connected to straight flush on board

[cjd]

Absolute Poker No-Limit Hold'em, $0.50 BB (9 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

BB ($24.65)
UTG ($21.98)
UTG+1 ($13.87)
MP1 ($40.35)
MP2 ($54.35)
MP3 ($51.25)
CO ($47)
Button ($53.44)
Hero ($100.15)

Preflop: Hero is SB with A[img]/images/graemlins/club.gif[/img], 9[img]/images/graemlins/spade.gif[/img].
<font color="#666666">3 folds</font>, MP2 calls $0.50, MP3 calls $0.50, <font color="#666666">1 fold</font>, Button calls $0.50, Hero completes, BB checks.

Flop: ($2.50) 7[img]/images/graemlins/club.gif[/img], 3[img]/images/graemlins/club.gif[/img], 9[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(5 players)</font>
<font color="#CC3333">Hero bets $1.5</font>, BB folds, MP2 folds, MP3 calls $1.50, Button calls $1.50.

Turn: ($7) J[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">Hero bets $1.5</font>, MP3 calls $1.50, Button calls $1.50.

River: ($11.50) 8[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">Hero bets $10.5</font>, MP3 folds, <font color="#CC3333">Button raises to $21</font>, Hero ???


Re-raise, or call since there are several straight flushes possible? (Button has $28.94 left after his re-raise)