Painful breast - had a clear mammogram and ultrasound didn't show anything but I'm still in pain. What should I do?

Hi. I had a mastectomy/chemo and radiotherapy 5 years ago. I now have pain in my other breast. I had a clear mammogram but told the nurse about the pain so they gave me a n ultrasound but couldn't see anything. I am obviously relieved but I am still in pain and don't know why. Any thoughts? I nad my ovaries out so not sure if it could still be hormone related. Not really sure what to do x