Hello~I am so sorry you are having these miserable symptoms. Are you under an abnormal amount of stress, I ask this because this can happen if the body is in a constant state of stress. You definitely need to be able to keep food in your tummy, I suggest maybe eating the smallest amount of food several times over the course of the day, also, add a good, high potency pro-biotic, this will put friendly bacteria in your tummy that you are probably, and this, too, can cause the nauseous feeling.
If it continues, then you really should see your doctor, it is probably not serious, but he/she can maybe give you something to counter-react the feelings you are having.
I hope you feel better soon. God bless you.
I’m 14 as well, and I went through this for about 2 weeks. How much are you eating? I ask because I started feeling sick like this after forgetting to eat often. All I really did to get better is pretty much just get back on a regular eating schedule, except for I would eat softer foods so I didn’t hurt my stomach. I was back to feeling ok after about a week. I hope this helps!!!