villain is 83/33/3 over only 25 hands. has called sizeable flop and turn bets twice w/ a bare gutshot draw

PokerStars No-Limit Hold'em, $0.50 BB (6 handed) Poker-Stars Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

Button ($82.35)
SB ($49.50)
BB ($55.85)
Hero ($78.55)
MP ($49.25)
CO ($57.80)

Preflop: Hero is UTG with Q, Q.
Hero raises to $2, 4 folds, BB calls $1.50.

Flop: ($4.25) 6, 8, 9 (2 players)
BB bets $0.5, Hero raises to $3.5, BB calls $3.

Turn: ($11.25) 2 (2 players)
BB bets $0.5, Hero raises to $7, BB calls $6.50.

River: ($25.25) 3 (2 players)
BB checks, Hero bets $17, BB raises to $37.5, Hero ???