Help with a Hand in $3/5 NL game

[xtwalker]

I posted this in another forum and a regular told me to try posting it here for input.

I think it was an interesting hand, and I think I played it pretty poorly. I would love to hear what some of you would have done in my possition... I'll start with a little backstory for the situation.

I had been playing for maybe 2-3 hrs and had taken a couple tough hits in big hands, but had also given a couple bad hits in big hands. Player A had just moved from my right to an open seat on my left for the declared purpose of getting better possition on me. Player A had about $600 and was playing a rather solid game but seemed to not like playing pots with me.

I just played a big hand from the SB where I flopped a wheel SF draw with As3s I checked, Player B bet, I raised, he pushed, I thought I had odds to call for the size of the pot and called. I hit my nut flush on the river and took down a $1k pot. Player B rebought for $300.

Two hands later I am in the cutoff with Player B limped-in UTG ahead of me, I held KhQh and I noticed that Player A (on the button) was holding chips for a raise. I decided to raise to $20 and see if he had a strong hand or if he wanted to play his possition. Player A calls the $20, and Player B calls the $20.

3 players to the flop, ~$65 total pot.
The flop came out 9hThAs.
Player B checks
Hero: ???? What action should I take here?