You can go to iTunes - DeAuthorize all Machines if you want.
Change your Apple ID Password First through iTunes.
Someone can buy all day long with an Authorized computer in your name.
Apple.com loads fine here in US.
Maybe you have a virus, are you on a PC or a MAC?
It may be too late to change Password if you've been hacked into - you will need to contact Apple.
Hopefully, the situation is not that bad yet.