What Causes Swelling In The Left Breast?

Hi. 58 yrs old male, swelling in left breast (mostly the top half) and nipple sensitivity. Within a week, further swelling and sensitivity in left bicep/arm and underarm. I went to ER when the breast swelled, blood was negative for infection then, and ultrasound seemed to indicate it was tissue swelling, Dr. said this tissue had always been there(?) Sent home urged to see a hormone specialist, yet since the bicep and armpit swelling has occurred. Also noteworthy is accompanying fatique, lack of appetite and shallow breathing (shallow breathing has come and go over the past three months, but back again now. MAYBE unrelated is a severe groin pain in right side, diagnosed as a likely result of degeneration in lumbar disc(s) L1, L1.5 and L3...prostatre cancer has been ruled out for the groin, and also possible tendinitis to explain groin. Back to gynocomastia and arm/armpit swelling and sensitivity...not sure hormone specialist is still the one to seek out. Thoughts??