I ate a lot of sugary foods today and i am now experiencing chest tightness and pain. i'm not overweight and i'm fairly sure i'm not diabetic. causes?

Unrelated: Sugary foods are not the cause of your distress. Like anyone your age , your pain is either related to a gastrointestinal or musculo-skeletal cause. Coronary disease in a 21 year old female is too rare to consider seriously. I see you're taking prednisone. A common side effect is abdominal pain. Is your chest pain kind of down low -like maybe coming from your tummy?