Unbelievably big decrease in Adsense for Youtube earnings. Reason? Solution?

I have old active Youtube channel and I became Youtube partner with that channel few months ago.
In first month of partnership my Adsense for Youtube earnings were around $700
After that, every month was in $0.8-$4 range in Youtube earnings.
Views dropped by 30% since that first month, but that can't be the reason that caused decrease in earnings by more than hundred times.
Can someone explain this or give me some advice how to fix this?
I can't contact google support because when I go to…
Unbelievably big decrease in Adsense for Youtube earnings. Reason? Solution?

See original post by umpahpah