How do i know whether my site got hit by humming bird update?

Hello Everyone

My website ( traffic has gone down from 500 visitors to just 10 or 15 per day. This has happened in September. How do i know what is the problem.

Almost 70% of the traffic to my site was from google. now not even 10 searches per day.

I did not get any message in google webmaster tools regarding penalty.

Can anyone help me and suggest any solution to get my traffic back.