Constantly feeling stressed??

It've been feeling constantly stressed for absolutely no reason. I'm 15 years old and don't have a job or go to school (I'm homeschooled. I still do lots of work but at my own pace) so I don't even really have a reason to feel like this. I have suffered from severe social anxiety ever since I was nine or ten, which is why I couldn't handle being in a 'school environment' as such, but I mostly feel like this when I'm home. I even went on a holiday with the family last week to try and relive some of the stress but I couldn't. I keep feeling like I need to go for a walk and it does help but when I get back I still feel the same. I love to write so I'm often off in my own world and I have been told often that I have little to no concept of reality. I don't know if that has anything to do with this but I think it some how might seeming as the stress is usually telling me I should be constantly writing.

I'm sorry for writing such a long paragraph but I just keep feeling like I've eaten a tub of salt and sometimes I even feel like I'm being stabbed in the left of my chest.

Anyway.. Thank you for taking the patients to read this :P