77: 9-high flop vs. PFR

I'm not sure what to do with hands like this where I may have the best hand on the flop or not. Should I be betting this flop?

$2/$4 9 players

Dealt to Hero [ 7c 7d ] in UTG
Hero calls, 2 folds, MP1 raises, MP2 calls, 1 folds, Btn calls, blinds fold, Hero

calls.

Flop [ 4h, 9c, 2c ] 4 players
Hero bets, MP1 calls, MP2 calls, Btn calls.

Turn [ Ks ] 4 players
Hero's action

I'm lost as to what to do at this point.