Fold.
Your stack is not so large that losing 9 BB will not worsen your position. And 99 is not the strongest hand in this situation. If we assume a typical range for such an all-in, then this will be the finished pair 99+ or A10 +. This makes your chances of winning 50/50.
Why are you assuming a typical all-in shove range when the Villain's behaviour hasn't been typical, though? He has been shoving abnormally. I would say you can add all pocket pairs to the range, but to be fair 55+. He had very likely been pushing with medium and lowish Aces, and KQ too.
I would assign him 55+A7+KQ. That's puts you slightly ahead. To be honest his range could be wider as well. It's a tough spot alright. I would consider the following.
How deep is the rest of the table and the blinds in particular. Is there a likelihood the blinds will interfere?
Middle and low pocket pairs lose value dramatically the more players enter. The lose value faster than broadways. If I had any doubt that blinds will interfere I would Fold, unless the blinds were below 6BB so I would have a chance to dominate the side pot.
Is the rest of the table shallow in comparison with you? If yes I would go for it. If not say 1 or 2 players have 15 bb+ I would not. Losing the pot would put you into disadvantage. On the other hand, you'd reaffirm your image that you won't be f with.
I think I'd be slightly pivoted towards folding to be honest because you dont know what the blinds hold. Although Im sure they'd be happy if you eliminated him. At best you are going for a coinflip pretty much, though the dead money is tasty. If I had JJ I would go in. I would fold this. It is a very hard fold though. If you were more shallow you'd need to call.
My 2 cents.