Radiation affecting bones

Hi, 56 year old male, stage 2 anal cancer. I went through chemo and radiation. My understanding is that the rad is pretty significant. I completed treatment 6 months ago. 2 weeks ago doc says I am in complete remission. Removed my port last Friday. I think I am doing great. Sunday early morning I end up in the ER in way worse pain than I ever had during cancer. Can barely walk, numb right side, feels liked I got kicked in the right nut and am basically bed ridden. Waiting for an MRI to check pelvis. Already had some disc degeneration at L5 S1. Does anyone have experience with bone issues due to radiation?