I had exactly the same email at about 4pm today. I've never logged into origin anywhere but my home pc and I haven't even logged in there for about 2 months.
You'll need to call EA on 0870 243 2435. I tried earlier but was kept on hold for 20+ minutes and gave up. They're open 9am-9pm so maybe give them a ring in the morning? I'll be doing the same.
Fingers crossed for the pair of us.