Hi, im a 21 year old male. Smoker since i was 19.

Been experiencing a warm/pain sensation in my left pectoral that tends to radiate occasionally across my shoulder, down my arm and hand. My hand can get cold sometimes too.
Im thinking it may be a nerve problem as i have minor pain in my neck left side too.

My doctor seems to think its a pulled muscle but i have been experiencing these feelings for over 2/3 months now.

Also, I tend to feel vague alot of the time and used to be a frequent marijuana user until 2 months ago when I quit.

All of this is really decreasing my quality of life and i just want to feel ‘normal’ again.
Is there any advice anyone could give me? Thanks