I noticed that you suspect pheochromocytoma in a lot of other cases in other communities too.
It is a very rare disease though. Are you really serious in your answers?
Highly unlikely, neuroendocrine tumors are very rare and usually presented in over 60 year olds. Why scare the OP with all the worse case scenarios? This is a 14 year old with a sudden onset of discomfort which could be anything from a pinched nerve or pulled muscle.
and what would cause the vasoconstriction in a 14 year olds heart?
A 14 year old coming on for heart attack?
We can't really say what's going on over the Internet, but it's most likely a pinched nerve in your neck or shoulder. If it keeps up you should have your parents take you to see a doctor.