Playing mid pairs, badly

[Analyst]

As I try and get used to SH, playing middle pairs (say, 99-66) is an area with which I'm struggling. Witness:

PokerStars 5/10 Hold'em (6 handed). Players are loose to very loose.

Preflop: Hero is CO with 6[img]/images/graemlins/diamond.gif[/img], 6[img]/images/graemlins/club.gif[/img].
UTG folds, MP calls, Hero calls, Button calls, SB completes, BB checks.

Flop: (5 SB) K[img]/images/graemlins/club.gif[/img], 5[img]/images/graemlins/spade.gif[/img], 2[img]/images/graemlins/heart.gif[/img] <font color="blue">(5 players)</font>
<font color="CC3333">SB bets</font>, BB folds, MP folds, Hero folds, Button calls.

Preflop, I figured that my best chance was for a limp-fest, which did occur but I don't know if this was the right move. Raising still leaves the prospect of a multiway pot and a board full of overcards to my pair; folding seems weak.

The flop play seems wrong, too. However, calling or raising would seem to commit me to a showdown (do they have a K or not?), with almost certain overcards coming, and lately I've just spewed 2.5-3BB too many times with an almost-dead middle pair.

Thoughts?