Soar Boobs went to the Doctors and everything was Good

Has anyone experienced soar breasts? So for the past wk my boobs have been soar, i went to the doctors to get checked and everything was ok , i had aslo took a pregnancy text and it was neg. My question is , What will cause the soar and could pregnancy be coming? or etc etc. i wear comfortable bras, and my period isnt till another wk.