Bizarre 6 max hand

How would you play this?

Limits 1/2.

Just sat down, no reads as yet except button seems LAG.

I pick up 99 in the sb. Three guys limp, i complete, bb checks.

Flop J57 rainbow. All check to button who bets, I check raise expecting to isolate. Only problem is everyone calls!

Next card is an 8. I check (?), utg bets, 2 callers, i hem and haw and call.

Next card is a 4 completing rainbow. I check, utg checks, utg+1 comes out of nowhere and bets, button calls, i fold, utg folds. utg+1 had a pair of 7's for the winner.

Comments? do you overcall this?