What Causes Pink Skin While On Radiation Therapy?

I am a lymphedema (OTR) therapist who does home care. One of my patients just started radiation to the Left quadrant. This is her third week. She is starting to develope pink skin and has special cream to apply to the areas. She is legally blind and has numbness in her hands and fingers. The left shoulder range was limited prior to my intervention . I have had past cases where the shoulder and axillia area became very limited and the skin on the arm would weep and tear at the slightest touch. I do not want this to happen to this new case. Any thoughts or suggestions. Thank you Diane Valentine