You need to stretch heaps to help with cording. I stretch my arm morning and nite in shower...i hang on to the curtain railing and it feels great. Also massage the area and use you fingers to pull away the area thats cording and you should here it pop sensation. Freaked me out the first time i did it but was given this advice by my breast care nurse and it works a treat. The more you use your arm the better.
Hope things improve for you its a bugger being in pain all the time i know first hand what that feels like. Take care.
Maryrose