question: Every evening I have a bad rash , very raised on my arms chest and legs, it also feels hot. In the morning the rash is very faint and by mid morning it is gone, only to come back again in the evening. What is it and what can I do.? I did hava chemo and radiotherapy together in January, but do not have cancer any more,.A week ago Ihad a cystoscopy and then the rash started. This happened three months ago after my last cystoscopy. Would this be the cause?