Having pain in my left arm. Alittle beneath the shoulder and it jst goes up and down. If I'm nt having pain there than the pain will start in My wrist?

Left arm pain. May be impingement of nerve at shoulder like thoracic outlet syndrome, or a bursitis causing nerve impingement ( does motrin like products releive it - if not allergic to these ?) May be brachial plexus issue or mass in the area ( clavicular ) pressing on nerve. Consider CXR, mammogram and follow up with orthopedics .