I can relate to that, mate. Healthy diet or random food? Do you have somewhat stable sleep schedule? Do you have a job? Do you hava a meditation habbit? If not, I suggest you to think of applying at least some of these to your life. It really helped me. Also, do you do any kinds of drugs (tobacco and alcohol too)?
From what I can tell, Ive started to feel better after ive commited to a meditation retreat and just sat on a couch for 3 days straight doing absolutely nothing without any food or entertaiment (at least dont eat alot and make sure its not junk food and ure allowed to drink water). While sitting try to be as still as you can. The whole point of it all is too overcome your desire to scratch head/nose, change position and stuff like this. I remember feeling anxious and frightened, at times, so you may mark these feelings as normal. After that my thoughts became alot more clear and ordered nicely, if that even makes sense...
Folks here, on this forum, advice to find a hobby or learn a new skill, this sounds reasonable.
Hope you get well, mate. i know how it feels.