What Causes Red Spots On The Left Breast?

Hi..im female 22 years old..and i've been having red spots on my left breast, since last november..the spots appear red and are 2 cms of diameter..then they start changing from red to light brown, then lighter, till they fade away, and i get more red spots the next day..im also experiencing a slight swelling on the other side of my left breast which hurts..I'm seeing my doctor in 2 days but shall i be concerned that it might be breast cancer? thank you very much!