Homepage disappears constant from Google

I have a website that is related to tantric massage. For a few months it goes up on the first page in Google for a few days and the homepage disappears from google after a few days, then it returns back to the first page. Simetimes apear in Google in page 2 Google but with another page, not with homepage. What can it be? Sorry for my english.

There can be temporary penalty because of sudden link change. Now it is back to normal so ranking gained again.

achiever2011 said:

There can be temporary penalty because of sudden link change. Now it is back to normal so ranking gained again.

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Nothing change at links from my site in last 1 year, but constantly disappear homepage from 1st page on Google and apear on 2nd page in Google but with another page.

alinmanea90 said:

Nothing change at links from my site in last 1 year, but constantly disappear homepage from 1st page on Google and apear on 2nd page in Google but with another page.

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Worst thing is that Google does not offer support for these type of unusual expeiences.