What Causes Pain Under The Armpit Along With Tingling Sensation In Arms?

I have pain / a feeling of pressure under my left arm pit. I smoke on and off but regularly chew nicotine gum.. I cannot feel any lump. I sometime get chest pain on the left and tingles in my left arm. Although I am addicted to nicotine I am relatively fit though. I have always played sports and go to the gym twice a week. When at the gym I cycle 10k and do not feel dizzy or have heart pain...so am a bit confused. I am 48

I have a theory that it could be some sort of clogging of sinuses on the left side. The left side of my head feels heavier and I cannot breath deeply on this side of my body..I have chewed the nicotine gum for many years and wonder if that is causing these problems. Any ideas ?
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