OK ... I definitely need some help with this one. I was fairly new to the table and had no good reads on anyone (my bad). As you can see, a number of players called the small PFR. Preflop I figured there were a variety of hands, mostly connectors, maybe a pocket pair or two, and at least one big PP. After the flop and my initial bet, I put the SB on AA, KK, or QQ. But then he comes back over the top ....

What to do?

No Limit Holdem Ring game
Blinds: $0.15/$0.25
9 players

Stack sizes:
Hero: $24.75
UTG+1: $41.00
MP1: $38.75
MP2: $39.55
MP3: $13.50
CO: $6.90
Button: $19.35
SB: $35.35
BB: $26.95

Pre-flop: (9 players) Hero is UTG with 6♣ 6♦
Hero calls, UTG+1 folds, MP1 raises to $0.5, MP2 calls, MP3 calls, CO calls, Button folds, SB calls, BB calls, Hero calls.

Flop: 6♥ 9♣ 7♣ ($3.5, 7 players)
SB bets $2.5, BB folds, Hero raises to $5, 3 folds, CO raises all-in $6.4, SB raises all-in $32.35, Hero ????