sore breast help?

Ashlyn
My breast is sore, not the nipple but the actual breast. Top of it, underneath of it.. just all of it. Anyone know why? Or how to make it better. 
We have a great latch, she's gaining weight as she should. There aren't any bump or lumps in the tissue. I've tried massaging and switching holds. Heating pads and cold packs haven't helped either. I did however have a red spot the size of a quarter on my breast in one of the places it hurt, but it has since then gone away... help?