good luck dude. You need to find the source. You've done the right thing by contacting Google. Keep doing it until you find out what is going on. Google has obviously investigated it and they didn't find anything irregular. Find out exactly why it's happening and enjoy the earnings.
If Google replied back with a positive answer, saying there's no problems.. then just sit back and enjoy the earnings buddy Just keep that email in a safe place, if something does happen. Maybe you've got a site that specifically targets a group of people from a particular time zone, and they go crazy on your site
ITs obvious someone likes ur site... you can track him and find out if he is someone u know,, use statcounter
Best thing to track would be to enable Google Analytics which helps you to find out the source of clicks and revenue. Might be receiving from some referral sites.
If you have problem with that you can always write above the ads don't click on ads, that can not be against tos
Thanks for the comments guys but I think the problem is solved... Google sent me email again telling me that the clicks were valid for some reason and they didn't find any problem...