A brown liquid or like a liquid is coming sometimes after perioud an d now is coming before my perioud with2 or 3 days before perioud.I don't know if I have to be worry.

It's just older/brownish blood, if it's really heavy or you are scared, or if it is BRIGHT red, that would be cause for concern. A doctor would easily be able to help you determine what's going on if you are very very worried, but I have some brown discharge before and after menstruation too.