It could be low blood sugar, anxiety or several other things. The best thing to do is see your doctor and go from there. If when you feel this way, eat a little something, and if you feel better it's low blood sugar. See your doctor for an evaluation. You're young so it's doubtful that it's anything serious. Take care.
Sounds like a panic attack setting In. Or anxiety. Have you or anyone In your family ever had anxiety and or panic attacks?