in which i call/call/call

I would raise the flop and maybe check/fold the turn, because I think a medium pocket (66s to 99s) is a wide range of his hand here.
He could be just beting his bad draw, but he chose a good spot. IMHO the pot is to small for calling down. Your investing 2BB to get 7.5BB. I don't see you ahead more than 27% of the time.