I agree, speak to your parents or doctor asap. As far as eating goes, start off little and often. Have half a slice of bread and butter if that's all you can manage right now. Then give it a couple of hours and try something else. You need to bring your blood sugar up to stop the shaking. Also, you can get drinks like build-up and fortisip from the chemist (are you in America?) to use short-term while you bring your appetite back. But please get proper help as soon as you can.