Trip J's Facing Pot Bet on River, Deep

Yatahay Network - $0.05 NL (6 max) - Holdem - 6 players
Hand converted by PokerTracker 4

CO: 110.4 BB
BTN: 128.6 BB
SB: 104.2 BB
BB: 126.2 BB
UTG: 100 BB
Hero (MP): 198.4 BB

SB posts SB 0.4 BB, BB posts BB 1 BB

Pre Flop: (pot: 1.4 BB) Hero has J♠ K♠

fold, Hero raises to 2.4 BB, fold, BTN raises to 5.4 BB, fold, BB calls 4.4 BB, Hero calls 3 BB

Flop: (16.6 BB, 3 players) J♦ 5♦ 4♠
BB checks, Hero checks, BTN checks

Turn: (16.6 BB, 3 players) J♥
BB bets 16.6 BB, Hero calls 16.6 BB, BTN calls 16.6 BB

River: (66.4 BB, 3 players) 6♥
BB bets 66.4 BB, Hero???

Does he get here with 44, 55, 66, or 78? What starts blasting on the turn other than Jx? Would he not have bet the flop with AJ? I figure it has to be KJ, QJ, JT, maybe some chance of AJ or QQ.