Why am I always shaking?

There are several possible causes, but one of the more common causes in USA is magnesium deficiency. The most common symptom is bed wetting. Magnesium strengthens muscles, calms nerves, stops cramps, and fights infections. Get epsom salt. It is cheap, five bux for a year's supply. Put a dose in a glass with water to cover and stir until it dissolves. Fill the glass with lemonade and drink it. You can take it without the lemonade but you won't like the taste. Milk of magnesia is more expensive but nicer tasting and gentler laxative action. Your choice.

Study some books on nutrition so you will know how to eat right.