About A Month Ago, I Noticed That My Arm Had

About a month ago, I noticed that my arm had been hurting. As if there was a pulling sensation from my wrist to my elbow to my armpit. It's a connected feeling and it feels as if my vein hurts but I am aware that veins do not hurt but that's the only way I am capable of describing my pain in my left arm. I cannot extend my arm up as if I were to raise my hand to ask a question. I'm on a team where we dance with flags and lately I haven't been able to use my left arm due to this rare experience. I've used a warm compression to ease the pain but moments later the pain returns.