QQ faces preflop heat OOP and flop comes safe... against unknown

[zach383z]

Villan is unknown, this is about my 3rd hand at the table, I really dont know what to do here against an Unknown?

PokerStars No-Limit Hold'em, $0.25 BB (6 handed) Hand History converter Courtesy of PokerZion.com

BB ($25.80)
UTG ($26.95)
MP ($22.25)
Hero ($28.20)
Button ($32.70)
SB ($24.75)

Preflop: Hero is CO with Q[img]/images/graemlins/diamond.gif[/img], Q[img]/images/graemlins/heart.gif[/img].
<font color="#666666">2 folds</font>, <font color="#CC3333">Hero raises to $1</font>, <font color="#CC3333">Button raises to $3</font>, <font color="#666666">1 fold</font>, BB calls $2.75, Hero calls $2.

Flop: ($9.10) 6[img]/images/graemlins/spade.gif[/img], 4[img]/images/graemlins/heart.gif[/img], 8[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(3 players)</font>
BB checks, <font color="#CC3333">Hero bets $5.5</font>, <font color="#CC3333">Button raises to $21.25</font>, BB folds, Hero?

Was my mistake not pushing preflop, or is that spewing? Does this look like a decent play, and is calling out of line to his push?