Geeeezy creeeezy, you're feeling the stress from GCSEs??
Do you mind me asking what you're worrying about? Is it you thinking you need good grades for future, or you pleasing your parents, or you beating friends, or you achieving the most you can? Or have you lost sight of all of those things and all you know is that you're stressed?!
I always felt a twinge of nerves when it got down to a few weeks away, then i wouldnt feel nervous until the day before, then id get excited.
You'll be fine with revision if you've done good classwork, then plenty of past papers and talking to friends over things you don't understand. The coursework will be done soon, just squeeze it out.