Red and sore under arm

Hi there fellow warriors, 

i was diagnosed April 18 had 7 FEC-T with perjeta and now on my 12th Herceptin. WIre guided lumpectomy and lymphnode removal followed by Rads which finished mid January.


i have now developed a large very sore red patch under my arm (cancer side) kind of like a bad shaving rash. I haven’t been shaving or changed any products I use.

Any ideas ladies?!