PokerStars No-Limit Hold'em, $1.00 BB (9 handed) Poker-Stars Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

MP2 ($30)
MP3 ($14.85)
CO ($81.90)
Button ($99.65)
SB ($99.70)
BB ($70.35)
UTG ($16)
UTG+1 ($53.75)
Hero ($101)

Preflop: Hero is MP1 with K, A.
2 folds, Hero raises to $4, 4 folds, SB calls $3.50, 1 fold.

Flop: ($9) A, J, 3 (2 players)
SB bets $4, Hero calls $4.

Turn: ($17) K (2 players)
SB bets $4, Hero raises to $16, SB calls $12.

River: ($49) 4 (2 players)
SB bets $40, Hero ???? (calls/folds/allinn)
Final Pot: $49

Villian bet weak on the flop. I decide to just smooth call for pot control on a rather uncoordinated board. Turn he donks bet again, so I raise to get the draws out. On the river he bets big even though he just smooth called my turn bet, and no draws got there on the river. What would you do here?

I'm shoving the river everytime

I shove. Villain hasn't shown any real evidence of strength until the river and it looks more like a bluff to me than a set/straight. If villain shows up with pocket 4s, take a note.