Pain on left arm after chest work out.

Hi Doctors, Yesterday after my chest workout I'm observing pain on my left arm just above the tricep head and below the side deltoids , the pain is coming from inside, the pain comes on movement and sleeping on the left side, so my question is what muscle group is injured and is it a severe issue?, I feel no pain on touch and no swelling externally please refer the picture and guide me what recovery methods need to done.Some things to be confirm there is no chest pain and I feel it's not related to cardiac issue, I need some advice on my injury. My pain severity is mild to moderate it's not bothering my day to day activities but I'm worried if it turns worsen and can i continue my other muscle group workout. Thank you