100nl - TPTK vs. shortstacked donks

[pwalsh21]

Poker Stars
No Limit Hold'em Cash Game
$0.50/$1 Blinds
6 Players
LegoPoker HH Converter

<font color="black">SB: $77.05</font>
<font color="black">BB: $47.05</font>
UTG: $119.85
<font color="black">Hero (MP): $100</font>
CO: $301.65
BTN: $158.60

<font color="black">Preflop:</font> Hero is dealt Q A[img]/images/graemlins/spade.gif[/img] (6 Players)
UTG folds, <font color="red">Hero raises to $3.50</font>, 2 folds, SB calls $3, BB calls $2.50

<font color="black">Flop:</font> ($10.50) 4 7 Q[img]/images/graemlins/spade.gif[/img] (3 Players)
<font color="red">SB bets $6</font>, BB calls $6, <font color="red">Hero raises to $27</font>, <font color="red">SB raises all-in to $73.55</font>, BB calls all-in for $37.55, Hero?

SB - 43/5.8/1.5, 85 hands
BB - Unknown, but seems donkish

SB had been bluffing a lot so his flop bet means nothing. Am I pot committed to calling this raise? I'm really not worried about BB, but SB looks pretty strong. He could easily have KQ (maybe QJ-QT/56) and I've also seen him make a few multi-barrel bluffs and basically play like an idiot. I think he has a weird 2 pair or set more often, though. Considering he's shortstacked, is this a call?

[Fonkey123]

Call.

[TownIt]

snap call.