PLO2 - AA87ss not sure how to play the flop

Open preflop without doubt and totally miss the flop. Not sure how to play against this donk bet.

My thought was he could anything that beats me at the moment: 2 pairs, set, and/or flushdraw. While I only had the aces and no nuts possibility.

PLO2 Hi (6 max) - Omaha Hi - 6 players
Hand converted by PokerTracker 4

Hero (MP): 127.5 BB
CO: 120.5 BB (VPIP: 18.18, PFR: 13.64, 3Bet Preflop: 0.00, Hands: 66)
BTN: 81.5 BB (VPIP: 12.50, PFR: 0.00, 3Bet Preflop: 0.00, Hands: 16)
SB: 141 BB (VPIP: 92.22, PFR: 2.22, 3Bet Preflop: 2.08, Hands: 272)
BB: 137 BB (VPIP: 18.52, PFR: 11.11, 3Bet Preflop: 0.00, Hands: 27)
UTG: 23.5 BB (VPIP: 85.71, PFR: 28.57, 3Bet Preflop: 0.00, Hands: 7)

SB posts SB 0.5 BB, BB posts BB 1 BB

Pre Flop: (pot: 1.5 BB) Hero has A♥ 7♠ A♦ 8♠

UTG calls 1 BB, Hero raises to 4.5 BB, fold, fold, SB calls 4 BB, fold, UTG calls 3.5 BB

Flop: (14.5 BB, 3 players) 5♣ K♥ 3♥
SB checks, UTG bets 14 BB, fold, fold