66 flop set... fold turn??

Dude was an unknown only 3 hands so far and nothing to note. He did tank when I raised him on the flop.

Merge Network $0.02/$0.04 No Limit Hold'em - 8 players -

BTN: $1.86
SB: $4.30
BB: $1.69
UTG: $2.86
UTG+1: $3.69
MP1: $4.45
Hero (MP2): $7.60
CO: $2.68

Pre Flop: ($0.06) Hero is MP2 with 6 6
UTG calls $0.04, 2 folds, Hero raises to $0.12, 2 folds, SB raises to $0.28, 2 folds, Hero calls $0.16

Flop: ($0.64) 6 8 7 (2 players)
SB bets $0.32, Hero raises to $0.96, SB calls $0.64

Turn: ($2.56) J (2 players)
SB bets $1.28,???? Hero raises to $6.36 ??all in, SB calls $1.78 all in

River: ($8.68) 9 (2 players - 2 are all in)

After looking back he tanks my flop raise then fires pretty strong on the turn. He is repping the nuts here right?? Can we fold this turn or the fact that he is unknown we need to call down? I overjammed but should I have just called turn?? I was confused after he flatted my flop raise then donked the turn. Any help would be appreciated. Thanks