the shaking is not medical related, try a lot of dry firing both at home and
the range. Have someone else load for you and have them stick an empty case in once in a while. Also, practice with a .22 lr. (Recoil is often the enemy of accuracy.)
BTW, You can actually drink too much water, your brain can swell like a concussion and people have died!
Best of luck
NRA Certified Firearm Instructor