Here's the hand I had to play last night and I need some advice on how could I have played this differently. I'm playing 2-5 no limit cash game. Started with 500$ and got my stack at 2200 until I got this hand. New guy joined the table, haven't played with him before, at this point we have about 10 hands left for the night until casino closes.
I'm dealt 9

and 9

UTG+1 and raise to 25$. The guy reraises to 85$ on the dealer button. I call the raise and it's just me and him in the hand.
Flop comes down 10

8

4

. I check and he bets 100$ and I flat call. the turn brings a 6

. I check again and he bets out 300$ right away, I THINK FOR A MINUTE AND MUCK MY HAND, the guy shows ace

king
I was sure he had a over pair but like I said, haven't played with him before so wasn't sure if he was making a move or not. What did I do wrong and how can I fix this in case i'm in another situation like this in the future. Thanks.