Why does caffeine and sugar affect me so badly?

If I have anything from a few pieces of chocolate to a few cups of coffee or soda my heart will start racing for hours, I wont be able to sleep, I will get nauseous, dizzy and I will start to feel really depressed, same thing if I eat sugar! I cant drink tea or coffee or soda or eat chocolate or candy, but especially chocolate and coffee, If I even drink half a cup of coffee my whole day will be ruined! And when I eat really sugary food like M&Ms, smarties, lolipops, cake, brownies, cookies, etc my throat will start burning and I will feel like im going to throw up! I just had a bunch of chocolate mocha cookies (biggest mistake of my life) and I feel like I might throw up soon and I feel very dizzy and I cant sleep :( why does it affect me sooo badly?