Breast swelling

Hello, I hope someone can help, I'm 48 post menopause, my right breast and arm pit swell up, my breast will swell up at least another cup size or more, my GP referred me to the breast clinic, I had a mammogram and saw the doctor, she said it was normal and age related but it keeps happening and always the same side, it's very uncomfortable and I'm self conscious about it, I have an autoimmune condition for which I take prednisolone and 6mp. I can't feel any lumps, I'm reassured that the scan was normal, sometimes I get the let down feeling (have breast fed 3 children)

Anyone had similar?