@cyclo Welcome!! glad you jumped in to say HI :)
Radiotherapy is cumulative so for at least 2 weeks after you finish the fatigue is horrendous, and my radiologist made me take 2 weeks off as I worked all the way through. My body was wrecked, I did recover though. I find since my recurrence and having Chemo the road back is exactly as you are experiencing right now. I can't do alot but am building everyday, I had to learn to walk again. I notice even now, I still have pain throughout, my legs and feet. I too like @Jane-Altona see an Exercise Physiologist who has had to build me from the ground up again. Its been amazing but there was NO WAY I couldve just started exercising, I needed professional rehabilitation and highly recommend it to anyone on the road to recovery to get started back into exercise. It will get better but may take some time. Hugs Melinda xo