Ok, appreciated your answers, thank you. I'm not so cautious as I thought... Need to improve somethings on accounts. When this kind of thing happen is very nasty.
Do you have 2fa enabled on poloniex(wish 2fa was available here too), if it's on there's nothing to worry about. just change your passwords. also check for unusual plugin
installed on your browser.
I don't have this 2fa enabled. When i received the email i just frozed my Poloniex account. Some time later same thing again (someone logged from a differente IP), so i frozed again. I cleaned computer too, i hope these things don't happen again. It's very sad.
This is the IP that tried to change my Bitcointalk password:
IP: 187.161.231.171