Breasts are sore, there is no chance of pregnancy, and i no longer have my period; as an iud was placed over a year ago. what could be cause?

Normal cycles: If you are having intercourse, you could be pregnant and should take a home pregnancy test to be sure. If no sex, it's possible to have breast soreness with each hormonal cycle. If any redness, tenderness, or fever, it could be an infection. If it worsens or persists more than one week, see your doctor for an evaluation. Rare endocrine / hormonal problems can cause persistent/worsening soreness.