Bottom set coordinated board, getting scared

[PoBoy321]

Interpoker $.50/1. The games were really good last night, some very loose tables, but still, this is a hand that started to get me worried.

Hero ($44.50) is dealt 9 [img]/images/graemlins/diamond.gif[/img]9 [img]/images/graemlins/heart.gif[/img] on the button. 4 limpers to me and I raise to $7 (I'm trying to thin the field a little, plus I've been trying to switch up my game by raising mid-PPs and SCs when I have position).

The blinds drop out, UTG ($49.81) calls, a few MP players drop out and the CO ($43.52) calls.

Flop: K [img]/images/graemlins/club.gif[/img]Q [img]/images/graemlins/diamond.gif[/img]9 [img]/images/graemlins/spade.gif[/img]
UTG checks, CO bets $5 into a $24.50 pot. I raise to $15 (I think that I should have raise more). UTG check/raises all-in, CO calls and is all-in. Is this an auto-call?

My thinking is that against any of their holdings individually, I am either a big favorite or have at least 30% equity. However, with two people in the hand, I could easily be against TJ for the straight and KQ for top two pair and would drawing to a 9 or a running pair.

Any thoughts?