Why is my upper arm swollen and tender. it's been like this for a couple of months. it's tender to the touch and it hurts when i bend the arm.?

See a physician now: Swelling and pain in the upper arm lasting "a couple of months" is by no means a finding that should be observed without a defined diagnosis.This can be anything from a chronic musculotendinous injury to an infection or an abnormal growth or tumor. Diagnosis may require imaging studies such as xrays or mri. I would recommend immediate evaluation.