I had no hand history with the opponent.

PokerStars No-Limit Hold'em, $0.50 BB (9 handed) from (Format: Bet The Pot)

saw flop|saw showdown

Hero ($82.90)
CO ($62.50)
Button ($48.25)
SB ($34.75)
BB ($15.35)
UTG ($17.50)
UTG+1 ($89.50)
MP1 ($52.60)
MP2 ($50)

Preflop: Hero is MP3 with , .
2 folds, MP1 calls $0.50, MP2 calls $0.50, Hero raises to $2.5, 1 fold, Button calls $2.50, 2 folds, MP1 folds, MP2 folds.

Flop: ($6.75) , , (2 players)
Hero bets $5, Button raises to $12.5, Hero calls $7.50.
If this was a mini raise I would have really considered folding. However, I thought there was a good chance that he was playing back at me because of the low cards on the flop.

Turn: ($31.75) (2 players)
Hero checks, Button checks.

River: ($31.75) (2 players)
Hero checks, Button bets $33.25 (All-In)
What's your move on the river? Thanks.