888 on the Flop

[sting]

NL 100 - Party 6Max

Hero limps UTG ($110) with 7 [img]/images/graemlins/diamond.gif[/img] 7 [img]/images/graemlins/heart.gif[/img]
4 callers including maniac ($200) to my left who has raised about 60% of hands (this being an exception) and the button ($75) who has been straight forward in his play.

Pot = $5ish
Flop: 8 [img]/images/graemlins/spade.gif[/img] 8 [img]/images/graemlins/club.gif[/img] 8 [img]/images/graemlins/heart.gif[/img]

Checked to Hero who bets $5
Maniac calls $5
Button raises to $30

Hero pushes. Thoughts?