Heat rash after radiotherapy

Hi all, I am almost 4 years post treatment. I do long walks with a group but just recently noticed when I take my bra off I have a blotchy rash under my treated breast. I always wear a breathable sports bra and not had this issue since 2015 when I was told it was due to normal healing. The problem did stop eventually but I am concerned it has now come back. One thing to note is I have recently gained a few pounds in weight as I wasn’t able to get out in the bad weather. Anyone had the same experience at all? I can’t find anything on the breast care sites apart from the symptoms which occur just after treatment.

hi old spice60, i finished rads 9 months ago. then end of february my breast was very red and  swollen. i went to drs who diagnosed breast cellulitis and put me on antibiotics after 4th course i was put on a 3 week stronger different antibiotic this did improve redness and swelling but did not clear it completley. i was refered to solihull hospital and saw a dr on thursday, he said it was not bacterial and that it was down to radiotherapy. I was also sent for my first mammogram since lumpectomy last june and so due to tenderness on top of other side effects of radiotherapy i was dreading it. the mammogram thank god came back ok. so it may be possible you are having another side effect from radiotherapy. i am seeing my surgeon for my yearly check the 26th june so he may explain a little more. hope this is of some help to you jo 

Sorry for late reply. I found out the heat rash was due to the unseasonably hot weather and wearing a bra which was too tight (I have put on weight recently). I have since splashed out on a good sports bra made by Adidas which was expensive but worth it.