SB is somewhere along the lines of 40/15/1.

Should I even bother to call his checkraise? I mean, he actually checkraised the both of us after a bet and a raise. The fact that he wasn't very aggressive postfl0p (never seen him make any moves) is scary also.

Call a safer turn? Dump anything but a 9 or 7? Just fold?

PokerRoom No-Limit Hold'em, $2 BB (5 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

BB ($8.00)
UTG ($60.00)
MP ($119.90)
Hero ($106.50)
SB ($99.00)

Preflop: Hero is Button with 9, 7.
1 fold, MP raises to $3, Hero calls $3, SB calls $2.50, 1 fold.

Flop: ($10) T, 9, 7 (3 players)
SB checks, MP bets $3, Hero raises to $12, SB raises to $21, MP calls $18, Hero calls $9.

Turn: ($73) 5 (3 players)
SB bets $20, MP folds, Hero folds.

Final Pot: $93