Why are my hands shaky?

Im 14, 5' 2'', 7.5st, and honestly my hands have been shaking for the past few days. I feel really weakk even though i've eaten enough, but eating dosent help!! I dont even know what exact foods to eat to get rid of this. I've been having headaches, like really bad and my doctor gave me tablets but that didnt help and whenever i eat i feel like its not getting to my body, just passing through my body, and i just keep eating but it dosent helpp!! Like im typing right now and my hands are shaking and both my arms ache like mad! I also have coeliac disease (allergic to wheat/gluten). PLeasse help my i dont know what to do i feel so weak and ill!!