AJ in MP

Preflop standard and on the flop i use to be calling too given odds of 1:10. he donked into 3 remaining players which seems to be strong and could be Kx but you require approximately 4 outs to call and the ace is frequently clean and if he does just have a draw like QJ or QT or 9x, you might consider 1- 1,5 Outs for Jx and a small chance to take a freecard on the turn and 0,5 outs you can consider for your backdoor straight door if T or Q appears on the Turn.

Overall its fine to call the flop once and see what the turn brings. On the Turn you have to call again otherwise you could have already folded the flop. you always have to keep the consequences of your previous plays in mind. calling the flop means that you also continue calling the Turn if you hit a J and you can raise if Ax comes down.

The Rivercard is pretty awful and bad for your equity and SB keeps being aggressive and bets again. You should fold the River. You don't beat many hands and you're most likely behind against both. SB will certainly have toppair+. assumed you've been in a headsup situation you should call off but since BU could still raise or at least call with a better hand, your hand becomes really trashy and you were supposed to fold instead of paying off.