I am 41 year old female, 5'4", 135 lbs in the middle of radiation treatments for breast cancer. Got a rash on my radiated breast which then spread like wildfire to my entire chest and arm. It continues to spread up my neck and down my stomach. I am taking metoprolol for heart palpatations (for over a year) and benedryl to control the itch (for about a week). Oncologist, dermatologist and family doctor are all stumped. Ruled out shingles and radiation rash and I do not have any food, pollen or drug allergies. The only other side effects are fatigue and muscle soreness - but those could be side effects from radiation also. I have been using a topical prescription cream but it does not seem to be helping. It's still spreading and continues to itch like crazy. Any suggestions?