NL100 AQs flops flushdraw

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Poker Stars - No Limit Hold'em Cash Game - $0.50/$1 Blinds - 9 Players - (LegoPoker HH Converter)

SB: $138.40
BB: $131.90
UTG: $96.00
UTG+1: $33.50
MP1: $100.00
MP2: $57.10
<font color="black">Hero (MP3): $93.50</font>
CO: $166.75
BTN: $98.50

<font color="black">Preflop:</font> Hero is dealt A[img]/images/graemlins/spade.gif[/img] Q[img]/images/graemlins/spade.gif[/img] (9 Players)
4 folds, <font color="red">Hero raises to $4.00</font>, CO folds, BTN calls $4.00, 2 folds

<font color="black">Flop:</font> ($9.50) 8[img]/images/graemlins/spade.gif[/img] K[img]/images/graemlins/spade.gif[/img] 4[img]/images/graemlins/heart.gif[/img] (2 Players)
<font color="red">Hero bets $6.00</font>, <font color="red">BTN raises to $15.00</font>, Hero calls $9.00

<font color="black">Turn:</font> ($39.50) 2[img]/images/graemlins/diamond.gif[/img] (2 Players)
Hero checks, <font color="red">BTN bets $25.00</font>, Hero folds

Pot Size: $64.50 ($1.95 Rake)

Should i go allin on the flop? Suspect he has a set here. What do you do i
n this situation with no reads?