What Causes Constant Pain In One Breast?

I have had breast pain in one breast for around five years now i have been seen at hospitals and everythings clear although the pain doesnt just come on lead up to my monthly cycle its on going i have tried changing diet evening primrose and none of these have worked i get told its lumpy tissue live with it i feel like im wasting doctors time going back now but the pain is sometimes very tiring having to just live with it i wish i could have this lumpy tissue removed ? if there is such a thing for the past 5 yrs i have lived with this its really becoming depressing now ?