Yeah, I have that problem too. Ever since grade 7, I've had no motivation for doing any kind of school work or projects. Nowadays, I can't even read a whole book. Every once in a while I pick one up, and read a few pages, but then don't even bother to continue. It might be ADD, or motivational problems. I think doing the work with someone else will help you be motivated and focused. Try to find someone supportive who will at least sit with you while you're doing your work.
Because it is stressing you out. take a break and go back to it stronger :)
Then you need something like a shower to clear your mind :)
cuz work f-ing sux