Stakes .05/.1 NL full ring

No read on opp.
Dealt to Hero Ah,Ks in SB

PF betting:
4 folds, CO raises to .2, Button calls, Hero raises to .5, BB folds, CO calls, Button calls

Flop: 7c9s5c
Hero bets .8, CO folds, Button calls

Turn: 7d
Hero bets 1.5, Button raises to 3
Hero? Do you believe he has something. I know I could certainly throw out a check raise on a scare card in his position. I don't put him on a 7,9 or 5. Do you?

Your move?