Hi thanks for asking question.
You are just 15 . So first of all don't think about death directly.
Here are few possibilities.
1.First because of
anxiety and related stressful study can lead
panic attack with sweating , headache and
chest pain with difficult breath.Try to solve problem rather then taking stress.do regular light exercise.
Yoga at such a young age will be best.
2.Second if you have fever, cold and headache then viral respiratory infections can lead such constitutional chest pain.
Symptomatic treatment done for it.If still problem chest x ray can be done.
3.By any unacoustemed activity or heavy weight lift can lead muscular strain and chest pain.
analgesic and hot compress helpful.
4.If you have allergy to certain substance then asthma congenital can be ruled out by
spirometry.
5.If still cause not clear rule out gastric problem that might lead to reffered chest pain.
I hope my suggestion will be helpful to you.
Dr.parth