What Causes Tender And Swollen Breast?

hello I am 24, A few days before my period started my breast were swollen and exstreamly tender to touch, I was overflowing my bras. now I seem to be fitting into them again. I started my period on the 25th when it was supposed to start. the 27th I had a pinkish gray rubbery discharge on my pad. it was about an inch long. I have also had extremely bad back pain on the left side that has brought me to tears (it felt like the back pain I had when I was in labor with my child minus the contractions/ cramping). that started 2 days before I started my period. I continue to have back pain but it is less sever after the discharge (it feels like a bad knot in my back that wont let up now) This pain doens't feel like the pain I usually have in the front of my abdomin when on my period In fact I have not had any cramping feeling in the front of my abdomen at all and the is unusual for me. All my pain is in my back. ( I also have fibromyalgia but this pain doen't feel like the usual pain I am in) Also my period has been lighter than normal. I have unprotected sex with my husband since I have my tubes tied, almost 3 years now since that was done. Any ideas as to what the discharge could be?