A sudden drop in Google rankings within one night ?

I don't know why my keywords rank drop from page 1 to page 3 in google search results ?
Some keywords for website:
diendanthammy.com - for example: "mat na tri mun" from the position 5 on page 1 to page 3, "thuoc tri mun" from the position 7 page 1 to page 6 and "tri mun dau den" from page 1 to page 2.

what should i do now?

 

I can help you. PM me with more details

 

It happened to me when i placed popunder ads on my blog. Did you do something similar?

 

Thanks you

 

No i did not. I need help. I did nothing wrong but my keywords keep dropping

 

Are you making links to that keywords with exact anchor text or you are also using open anchor text?

 

A lots of people experienced drop in rang this days.

It looks like Google updated engine according to new guidance https://support.google.com/webmasters/answer/66356?hl=en

 

you can consult with an SEO expart, or you can PM me.