What Causes Burning Pain And Darkening Of Breast?

Hi I ad a core biopsy two months ago and the results were negative, my breast was black at firts and sore, the color start to change, but the pain became like a burning pain and I got a lump and the skin became hot and red,I went to my dr.yesterday,and after an ultrasound there was no hematoma like he thought he send me home without a answer and told me to call him in four days to let him know if the situation as changed.
Any thoughts please,
Thank you, gabriela