Hello @jeanalder and welcome to Mayo Clinic Connect. I am sorry to hear about your on-going bouts of fatigue following radiation treatment. Fatigue can be so challenging.

That said, I wonder if you have interest in journaling your health and lifestyle symptoms for a couple of months to see if you can pick up on any particular lifestyle or nutritional reasons that could be contributing to an onset of a bout with fatigue since it doesn't sound like it is ever-present?

Sometimes, dietary intake alone could be helpful to understand along with overall mood and movement trends.

Is there anything you can think of off the top of your head that are present just prior to experiencing a bout with fatigue?