Sharp pain in my left upper arm then the feeling of extreme weakness for about 3 minutes then normal again. it is not my heart i have a full check up.

Arm pain: Did your heart exam include a treadmill stress test? I would be thinking of a pinched nerve causing this symptom possibly from a neck vertebral spur or bulging disk. Tendonitis in the shoulder is less likely. Associated weakness is unusual but could be a nonspecific reaction or anxiety about the discomfort. If symptoms persist consult an orthopedic specialist or neurologist for evaluation.