My opponent is 30/5 and I put him on medium PP. I seriously doubt he has 55 or 88 because he check raised the flop. How do you think I played this hand? And what do you do against his river bet?

Full Tilt Poker
No Limit Holdem Ring game
Blinds: $0.50/$1
9 players


Stack sizes:
UTG: $39
UTG+1: $122.35
MP1: $99
MP2: $233.95
MP3: $109.90
CO: $87.25
HERO: $95.80
SB: $91.50
BB: $211.80

Pre-flop: (9 players) HERO is Button with
UTG calls, 2 folds, MP2 calls, 2 folds, HERO raises to $5.5, 3 folds, MP2 calls.

Flop: ($13.5, 2 players)
MP2 checks, HERO bets $10, MP2 raises to $30, HERO calls.

Turn: ($73.5, 2 players)
MP2 checks, HERO checks.

River: ($73.5, 2 players)
MP2 bets $30