What Causes Painful Lumps In Breasts And Armpits?

I have pain in my left breast and has several lumps that I was told are benign but for the past two weeks I have been havin pain and heat in my breaststroke and pain in my armpits and in my right arm which is currently swollen I went to a doctor las week and he said it was because if the skin tag on my back which has suddenly started growin