Heart Palpitations when I raise my arms?

So, I kind of have weird palpitations that I have been feeling. About 2 weeks ago I started feeling arm pain which led to shoulder and neck pain. I went to see my GP and my heart sounded fine, and my blood pressure and heart rate we’re fine. I have tried stretching and some working out, and have improved my arm and shoulder pain, but my back and neck still feel very sore. I run consistently and I feel fine with that, just a bit of back and neck stiffness. Another thing I started noticing was that when I raised my arms I felt a thumping sensation. I have been dealing with on and off heart palpitations for a little while and don’t know what they are. My posture is not great and I am pretty convinced I have a pinched nerve. Could that be the cause of my palpitations? I’m reluctant to think it is a heart problem because of how I am able to run and not have an issue.