Tourney hand - where did I go wrong?

[dragoncorpinc]

Long time reader, first time poster. Hope to get some pointers.
Live tourney hand 10 handed.
Everyone has the same amount of chips (7000).

Hero is in button with 5c5s6c10d
7 limpers, Hero calls, SB completes, BB checks

Flop: 9d9c5d (700ish in pot)
BB bets 150, MP calls, MP+2 calls, Hero raised to 1050
BB calls, MP calls, MP+2 calls

Turn: Ac (approx 5510 in chips in pot)
BB checks, MP checks, MP+2 Checks, Hero bets 5510
BB fold, MP folds, MP+2 goes all in, Hero calls 650

MP+2 shows AsKdJd9h and Hero loses.

Line of thought:
- 3 callers on the flop I put at least 2 players with a 9 and didn't hit their kicker yet.
- Only hand we are worried about on flop is 6h9s

question is:
- on the turn, how many people check on the button when it was checked to
- if you did check and MP+2 pushes river, would you fold or call?
- did I play it bad or did I get unlucky?

Thanks in advance.