$20+2 - Defending BB

[Aver-aging]

Sorry guys, I can't seem to get the Hand History Converter to work. But here it is anyway.

Villain has been raising almost every orbit in late position. I have defended my BB successfully from him earlier stealing a pot on the river. He has not shown down very many hands, but seems relatively aggressive.

50/100

Villain - t2005
Hero - t2005 [Ac10h]

All fold
Villain raises to t300 from CO
Hero Calls t200

*** FLOP *** [Jd 9s As]

Hero Checks
Villain bets t400
Hero ????

I realize that checking that flop to him may have been a mistake, as it does not give me a clear picture of his hand. I'm not sure though, what do you guys think?