NL50 SH TPGK against a river donkbet

[castor11]

$0.25/$0.50 No Limit Holdem
5 Players
Hand Conversion Powered by weaktight.com (http://weaktight.com/)

Stacks:
UTG ($50.25)
CO ($69.66)
hero (BTN) ($68.37)
SB ($47.63)
BB ($65.15)

Pre-Flop: ($0.75, 5 players) hero is BTN :kh: :ad:
2 folds, hero raises to $1.25, 1 fold, BB calls $0.75

Flop: :5h: :7d: :qc: ($2.75, 2 players)
BB checks, hero bets $2, BB calls $2

Turn: :ah: ($6.75, 2 players)
BB checks, hero bets $4.50, BB calls $4.50

River: :2h: ($15.75, 2 players)
BB bets $12, $12 to hero ($60.62)?

[Lev729]

Unpleasant situation...
There are no draw OTF (maybe some oesd/gutshot) , so he has few busted draw OTR.
I think it is backdoor flush, Ax and sometimes bluff (because of the high river agression)
He seems to be fish so I think call is fine.