Have you tried any fidget toys?
Fidget toys help people calm down and concentrate. Maybe you have a mild version od ADHD, so you can slow it down with fidget toys.
I've created a list of best fidget toys for all people, who are having a problem with ADHD and concentration while working or studying.
Here's a list of top 9 fidget cubes -https://sites.google.com/view/fidget-cube/
Here's a list of top 11 fidget spinners - https://sites.google.com/view/fidget-spinners
It could be ADHD, could be depression or it could be a neurological disorder. You need to see a physician and tell him how you are feeling. He can diagnose you better and get you on a good treatment plan,