Sometimes I feel a little irritation in my left shoulder and when I rotate my shoulder I can hear popping sounds. In past few months I had palpitations issues and ate beta blockers and ok with that now and then had allergic bronchitis. Though I still get thick and sticky mucus from my mouth sometimes my doctor says that you don't need bronchitis medicine anymore. Ok so that was my medical history. Now can you suggest why these left should pain and popping sound and what kind of doctor should I see?