I know you are not Doctors but I feel at my wits end with it.
It's probably been about three years now but I started off with tingling/ light pain in my back between my pain and shoulder blade left side. Quite often it was irritating as it felt itchy too. I was aware it was there every day.
Skip today it's more painful. I worked a 12 hour shift yesterday and between that should blade and spine it's very painful today since I've gotten up, it's much more comfortable sitting down. These days it also hurts my left ribs and when I lift my left arm, my left arm feels sore on the inner side. It feels weaker and more difficult to lift, like it's tight.
It's probably been a year + since I've been back to the doctors with it but at the time I tried physio and also had a chest X-ray