NL100: Donkbet on drawy board from an unknown

[Aquadougs]

Unknown opponent

Party Poker, $0.50/$1 NL Hold'em Cash Game, 5 Players
LeggoPoker.com - Hand History Converter

UTG: $100
CO: $104.88
Hero (BTN): $99.50
SB: $130.91
BB: $60.63

UTG posts $1
Pre-Flop: XX dealt to Hero (BTN)
UTG checks, CO folds, <font color="red">Hero raises to $5</font>, 2 folds, UTG calls $4

Flop: ($11.50) Q[img]/images/graemlins/spade.gif[/img] 9[img]/images/graemlins/heart.gif[/img] 3[img]/images/graemlins/spade.gif[/img] (2 Players)
<font color="red">UTG bets $5</font>


What is does that mean?
What should hero call with here?
What should hero raise with here?