I've had 7 months of upper back pain. Which started in my left chest, and radiated into my breast.
I thought I had breast cancer, I had my breast checked twice - nothing.
It eventually spread into my shoulder, left arm, down my back, up into my neck, around my shoulder blade and into my serratus anterior.
I couldn't put my hair up without my arm going weak and couldn't put my arm behind my back without throbbing pain and aches.
I started to get numbness, pins and needles, burning sensations in my breast... was all really scary stuff tbh.
I had an MRI thinking it's a trapped nerve and all came back fine.
I realised that my anxiety and stress made it worse, I was tensing up my shoulders and my chest which was causing intense spasms in my muscles.
I still don't know what really caused the issue but, for the past few weeks I've been getting much better, mostly because the MRI showed there was nothing wrong, my stress levels suddenly decreased.
I do Yoga twice a week which keeps my muscles stretched and keeps trigger points at bay.
I think this is something I will have to do long term now as my muscle is so fatigued on that side, it needs to be strengthened which will take time.
I just wanted to comment because I felt like you at one point and was crying daily with pain, put on medication all sorts... I'm not on the medication anymore and I've stopped believing it's anything serious, simply because it makes my stress levels worse.
Please talk to your doctor and let them evaluate you properly before jumping conclusions. If you have the money see a physio, sports therapist or chiropractor.