5-10 NL hand need help

[D.J.]

5-10 NL hand at the bike last night, I played several hands badly, and this one bugs me. I have KQs in 2nd position and make it $35 to go with $1100 in front, I get called in 3 places, 1 guy in MP who is running over the game, the CO who is a decent player and the BB. Flop comes

J-9-9 rainbow

BB checks, I check, and it gets checked around, Turn brings a Q, BB checks, I bet $125 and get called only by the MP guy with about $2K in front. This MP player doesn't seem very solid at all but has been running into some hands and had a good rush, when he calls I put him on a 10 with a possible pair like J-10 or Q-10, so if he doesn't hit a straight card I'm ok. River brings an offsuit 7, no threat, I bet out $250, and he quickly calls and turns over K-10 for the high straight. How did I play the hand and what should I have done differently, my game sucks of late and I am in need of advice.

-D.J.