Trying to understand . . . you hurt your elbow when picking a pimple by your breast, correct? So, when you squeezed, it hurt, correct? Okay, true thing about me. I have a place that I'd describe as the top of my forearm that gets tight. If I massage that, I swear I feel a twinge in my neck on the same side. Our body actually has 'bands' that run along it. I have a son who is a runner and there is a common injury I never heard about until he became competitive and this happened to a few team mates. iliotibial bands they are called or IT bands. Right? Who knew. Our bodies are very intertwined. The pectoralis minor muscle has trigger points that are all over along arms and hands as well. Who knew. Anyway, agree that referred pain could be happening due to nerve issues or it had to do with how you were tensing the muscles of your arm. Our bodies are complex, aren't they?
Google myotomes and dermatomes.
"In referred pain ... [w]hen the general visceral sensory fiber is simulated, the central nervous system does not clearly discern whether the pain is coming from the body wall or from the viscera, so it perceives the pain as coming from somewhere on the body wall, e.g. left arm/hand pain, jaw pain."
Check out an anatomical chart of the nerves. I have noticed that sometimes if I scratch somewhere on my shoulder, I feel a nerve pain in the center of my back. I assume it's because the same nerve is involved.