How do you close the gap?

Since sunday i have been feeling very bad about a particular subject.

I'm even waking up in the middle of the night with sort of 'panic attacks' (not real ones, but like the shock you get when you think you lost your keys or something..), have had terrible sleep and i can't stop thinking about what i don't want.

Obviously, things are not turning for the better for me, since i've been having these thoughts. Somehow i can't seem to get past it, and start feeling good again, where i could before. I need to break the cycle, because i have been creating a wonderful thing that i don't ever want to lose again. But it's becoming a negative vortex: i'm very tired, feel negative and the more i feel bad, i beat myself up over feeling bad and i feel even worse.

What do i do?