KK facing flop raise

[nietzreznor]

Pokerstars 1/2 (5 handed)

I am SB with KK. UTG folds, CO raises to $6, Button folds, I reraise to $17, BB folds, CO calls.

Not much of a read on CO, seems decent and not overly loose. I have $200 to start, he covers.

Flop ($36): 752r

I bet $28, CO raises to $100, I...

Could be a set, but I was worried more about AA... not sure how often I see something like QQ/JJ, or a bluff here.

Whats my move?