Fatigue post radiation

Hi
I have put other posts on here about the fatigue. I just find I feel like I'm on a roller coaster I'm 15 months from completing radiation. I feel like things get better and then I will have a day where I can hardly get out of bed I cannot understand this. I'm starting to worry there's something else wrong. All my blood works normal except for the fact I have anemia now not sure if that's causing this roller coaster. I have days where I just have no hunger and stomach aches and then I will feel really hungry for a day and want to eat all day this never has been the way I have been it's only since radiation. I also have fibromyalgia but it was pretty tolerable prior to radiation