Well, something is definitely going on.
Today I've had messages from Google telling me that someone in the US has been trying to sign in to both of my email accounts. Google stopped this from happening, and told me to change my passwords, so I have.
And now I can't get into my Facebook account. Facebook keeps telling me to enter the code that they've sent to my phone, and telling me that they are having problems changing my email address. I don't like this at all, particularly as they haven't sent any code to my phone - not that I'd asked them to in the first place - and I haven't changed my email address.