email account spammed/hacked?

[ArmageddonOuttaHere]

hi, basically i woke up to a few emails from mailer-daemon with message send failure. my friend had this before but he was also tweeting spam on his twitter account wheras mine is just my emails at the moment. I only use this email on trustworthy sites like facebook, youtube and xbox. i dont use dodgy websites and i never click any ads or whatever. the only thing i can think of is that i accidently clicked a link from from a fbook page post (a 'bit' link). i looked at my recent yahoo activity and it was logged into from poland so its definately had something done to it. i have changed the password but is there anything else i should do?

thanks