Although I do not have any advise, I wanted to send healing thoughts your way. It's bad enough dealing with your disgnoses. Having to deal with an infection also, seem overweening at times.
I would think that you are seeing an Oncologist but that may be who you have referred to here as the Rad dr. I believe I would definitely see your Surgeon and get this infection taken care of BEFORE any Radiation treatments. Radiation can delay healing and isn't usually started until complete healing has taken place. Regards .....