10/20 flopped set

[Brom]

This game is in an Ontario casino so it is played 11 handed, if that makes any difference to anyone.
The suspects for the hand are as follows:
SB is a by the numbers, newish, young, fairly predictable type opponent.
UTG is a new player to the table, also young, can be aggressive but not necessarily at the right time, and possibly on tilt.
My table image is what I'd describe as good at the moment, people fear my raises, and I have a high percentage of showdowns won. I'm in the BB on this hand.

On to the hand in question.
UTG brings it in for a raise, MP1 cold calls (this lady cold calls a lot of raises), folded around to the SB who thinks for a bit (looks to be calculating his odds + it's late and he's tired) and he cold calls as well, I call in the BB with 55.
Flop comes down 345 rainbow, SB checks, I check, UTG bets, all 3 other players call the bet.
Pot is now 6 big bets and the turn brings an offsuit 9.
Here is where it gets tricky. The SB and myself both check again, UTG bets out, MP1 calls, SB raises to 40. The pot now contains 10 big bets.
I basically don't like my play from this point on, could anyone offer up some ideas as to what they'd do in this situation and why? Thanks for any input you may provide me.

[Brom]

OK I just realized I posted this in the wrong forum, so I'm going to relocate it.