Help figuring out what happend to my niche site

Hi everyone, and thank you for taking the time to read this, let me explain what happened

I have a micro niche site

I've been on #1 on first page for exact match of my site for 5 months now

the keyword is a two word key word like this word1word2

strange thing happened today.

My site is first for word1 but not for word1word2

Also if I do a search on google like site:mydomain

it will show all indexed pages of my site but not the main page, that means
the site dot com on its own not a particular page.

Please help me understand this.

Thank you

Just sit down and wait for a week. Google is "dancing" a lot these days.

If the problem persists, checkout webmaster tools for any penalty or something like that.