Villain is 30/25 good lag. What is going on? Is this some thin value or bluff or nuts or what? Does my hand not look like a flush?

He took a weak line, so I thought: "I'll make a small bet and snap a raise". Then he raised pretty fast and I started convincing myself to fold. What's my optimal river play?

Full Tilt No-Limit Hold'em, $4.00 BB (5 handed) - Full-Tilt Converter Tool from FlopTurnRiver.com

MP ($400)
Hero ($660.80)
SB ($580.90)
BB ($406)
UTG ($860.40)

Preflop: Hero is BU with 6, 5
UTG bets $12, UTG+1 calls $12, Hero calls $12, 2 folds

Flop: ($42) 10, A, 3 (3 players)
UTG bets $32, 1 fold, Hero calls $32

Turn: ($106) Q (2 players)
UTG checks, Hero checks

River: ($106) 7 (2 players)
UTG checks, Hero bets $42, UTG raises to $184, Hero?