Someone else changed my Apple ID Password

Hello Guys,

I think I've got a problem with an ex girlfriend. We broke up last week blablabla and so I changed every password I known.

I only forgot the security question. An our ago I recieved an e-mail that my password was changed. I think she knew the awnser on that question and choose an other password. (Yes I've changed the question today after the password change)

I don't know for sure, but I would like to know from wich IP adress my password has been changed. Where could I find such thing? Or do I need to call Apple and they can check it out?

I hope somebody can help me a little further.

Thank you!

- Nickdhnick