Flop decision: top pair weak kicker under attack

[StellarWind]

Paradise Poker 2/4 Hold'em (8 handed) converter (http://www.selachian.com/tools/bisonconverter/hhconverter.cgi)
SB is normal/passive, UTG+1 is a LAG, and CO is generally very loose/passive but unpredictable.

Preflop: Hero is BB with K/images/graemlins/spade.gif, 7/images/graemlins/heart.gif.
UTG folds, UTG+1 calls, MP1 folds, MP2 folds, CO calls, Button folds, SB completes, Hero checks.

Flop: (4 SB) 5/images/graemlins/heart.gif, K/images/graemlins/club.gif, 4/images/graemlins/heart.gif <font color="blue">(4 players) </font>
<font color="CC3333">SB bets</font>, Hero ???

What do you do here and what is your plan?

[joker122]

I think this is an easy fold with 3 players to act behind you.

[StellarWind]

Sorry, there was a problem with the hand write up. I know it says five players saw the flop but there were only four players: SB, Hero=BB, UTG+1, and CO.

I have edited my original post.

Bison, the HH was a little odd and the converter introduced a phantom player which I tried to edit out before I posted the hand. I'll PM you with the HH.