Short Periods Of Arm Pain Concentrated In Shoulder Joint, Rotator Cuff Area, Spine Of Scapula With Throbbing Headache. Any Insights?

Hello,I am a 20-year-old female and I wld greatly appreciate your insight on my problem. For over a year now I ve been having short periods of left arm pain mainly concentrated in the shoulder joint , rotator cuff area and spine of scapula . I thought it was because I slept on my left side but I tried changing my sleep position but it still occurs. Also the pain now comes with posterior upper back pain and a throbbing headache concentrated in the lower left occipital lobe. I have a 10 minute walk to class everyday and after it I wld have fast breathing and palpitations. However, sometimes without any prior trigger (exercise, eg.) I would be sharply aware of my fast heartbeat and heavy breathing, and may feel chest tightness. (I take a lot of deep breaths). When I was younger I had wheezing and an asthma-like condition but I grew out of it. Sometimes I also get a left ear ache with/without the headache and I strongly believe my left submandibular lymph node is more prominent than the right. This was noticed over three months and it still feels the same. I ve been hesitant to see a doctor because I am worried about a heart condition or cancer, but I plan to do so soon.Thanks much for your insight.