Painful Breast after Reduction

I had a breast reduction about 4 years ago now. About a year after my surgery I started getting pains near the scar line of my right breast. At that time I went to my doctor and was told to have an ultrasound. The ultrasound picked up nothing other than 'normal scar tissue'. Since then I have continued to get strong pains and different times of the month, mostly around when I am due for my period. However these are not normal menstrual causing pains. They are isolated to a small area and are very very painful. In the last 6 months or so they have started to get a bit worse and once again was told by my doctor to have an ultrasound, which again picked up nothing.
I am really starting to get frustrated as no one can give me an answer. Is this normal? Is this something related to the surgery that I just have to accept? If so fine, at least I know and dont have to worry that it is something more! Please help!