Ok so this is not my field of expertise and i don't know how to exactly search for it in google. But today during therapy we came upon a conundrum whenever i was stretching out half of my pectorals muscle, by stepping into a doorway with my arm 90° against the wall, the opposite arm would go pins and needles. Then when i switched arms for stretching the other arm would go pins and needles. My therapist thinks my nerves are crossing over, and is going to think on it because it is a bit weird. anyone know what this is by any chance.