I am wondering if this might be muscle related or something else. I work in retail and do use left arm for reaching and stretching quite a bit. I have pain left side under armpit, going into armpit and upper arm and pain around to my back in about the same area as armpit. I am also 63,.
Hello, As this pain will be due to degenerative changes in the cervical spine and nerve entrapment. Due to which there is a weakness of the muscles and also the pain.  At 63, we can expect some changes in the normal physiology of the soft tissues and the Symptoms due to which are possible. Using neck collar, hot water fermentation, static neck exercises, shoulder stabilization exercise is recommended to help reduce the symptoms. Hope I have answered your query. Let me know if I can assist you further. Take care Jay In Chat Doctor.