AQo from BB against a lucky LAG

[TheWorstPlayer]

OK, this has been villain's night. You know when there is just one guy who has been getting every hand? That was villain. He had already built a big stack by flopping sets against big pocket pairs about 3 times in the past hour. He also flopped a straight against someone else's set. Just every hand was going his way. However, it looked like he was being very aggressive with the big stack and buying a few pots. The key thing I had noticed when he had flopped his sets was that he just smooth called the overpairs' bets, even though there were draws on the board. In fact, he smooth called once with an all spade flop when he had flopped a set. So, this is the hand:

Ultimate Bet No-Limit Hold'em, $.25 BB (5 handed) converter

saw flop|<font color="#C00000">saw showdown</font>

Button ($24)
SB ($16.65)
<font color="#C00000">Hero ($47.20)</font>
<font color="#C00000">UTG ($91.50)</font>
MP ($3.80)

Preflop: Hero is BB with A[img]/images/graemlins/diamond.gif[/img], Q[img]/images/graemlins/club.gif[/img].
UTG calls $0.25, MP folds, Button folds, SB completes, <font color="#CC3333">Hero raises to $1.25</font>, UTG calls $1, SB calls $1.

Flop: ($3.75) A[img]/images/graemlins/spade.gif[/img], Q[img]/images/graemlins/diamond.gif[/img], 9[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(3 players)</font>
SB checks, <font color="#CC3333">Hero bets $3.75</font>, UTG calls $3.75, SB folds.

He just calls, which starts to worry me, but I think that he could be holding something like KQ[img]/images/graemlins/spade.gif[/img] or AK. What should I do on the turn?

This is what I did:
Turn: ($11.25) 4[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets $11.25</font>, UTG calls $11.25.

Another smooth call has me pretty worried about a set, since this is a big turn bet to call with a draw. Should I shut down? Blocking bet on river? Where should I go from here?