3/6 Live vs. flop and turn donk

[Tiburon]

I just turned 18 about a month ago so I've been able to go to the local indian casino and play some live poker for a change. I usually play 1/2 online and 3/6 is the lowest they offer, but it is a weaker game than the average .5/1 online game so I posted it here.

Anyways, first hand at the table (no reads), 9 players.

Hero dealt A [img]/images/graemlins/spade.gif[/img] Q [img]/images/graemlins/heart.gif[/img] in EP2.
Hero raises, folded to CO who calls, SB calls, BB folds.

Flop: Q [img]/images/graemlins/diamond.gif[/img] 6 [img]/images/graemlins/club.gif[/img] 8 [img]/images/graemlins/spade.gif[/img]
SB bets, Hero raises, CO folds, SB calls.

Turn: 7 [img]/images/graemlins/diamond.gif[/img]
SB bets, hero ???

This game is usually loose and passive, most players don't even know what a c/r is so they just bet out if they hit their hand, which is why this donk bet worries me. Is this just a standard calldown vs. an unknown or should I put in another raise?