What Can Cause A Lump On Shoulder After A Snap Feel?

Hi, I recently felt a snap like a muscle tearing or breaking on the top of my shoulder, this was about a month ago. I go to the gym and a know what a strained muscle feels like. This felt like any other stained muscle except after a week 90% of the soreness/pain is gone but it's not getting any better. A month later there is now a bump/lump on my shoulder, it's sore to the touch and it still hurts hurts when i stretch my arm into certain positions. Is this something I need to see a physician about?