Suspicious activity on my infoproduct site?

Can anyone tell me how I can tell if my website has been hacked? And is it possible for a hacker to somehow redirect my sales? My sales have dropped to next to none for the last 2 and a half weeks and at the same time, my foreign site traffic has skyrocketed. Is that suspicious? Normally, I have several sales per day for the last 2 years. Now all of a sudden, I get maybe 1 small sale every couple of days. Something seems wrong.

I have checked my Google rankings to see if my ranking had dropped and that would explain a sudden drop in sales but my ranking is still excellent. Out of the blue, my site is now getting almost 20% traffic from Google Australia, Brazil, Mexico, Ireland, Belgium, Philippines, India and Singapore. My U.S sales have dropped to almost nothing and the few sales that have come in are from these other countries. My target market & SEO efforts are only for the United States. Also, an ad that I run that typically brings in a ton of sales per day is now running and people are clicking on it but no sales. I find that suspicious too.

I checked my Google Webmaster account for my site and there are no security alerts/flags. I also signed up for Godaddy's Website Protection and ran the scan and that came back fine however after that, it keeps saying an error occurred when I try to launch the scan to rescan it again.

Any advice/thoughts? Am I being paranoid? How can I check it to be sure?