Nea-adj chemo-rad was pretty intense for me. I know some other RC'ers that cruised (comparatively) through. My tumor was a low rectal variety, so the side effects were related to that area, but as good as they are at targeting, there is going to be biological blowback. Primarily from the tissue around the targeted area and 'downstream' of the beams. The southern parts of my urinary tract were drasticly effected, even ones that weren't adjacent. Also, the radiation itself can steamroll you.
I don't have any magic tricks, but to say you may need to fight fire with fire and up the positive interventions with pills and rest. Maybe talk to your doctor about mixing and matching meds. A pre-zap ativan stacked with zofran or emmend and a good long nap right after treatment. At least with radiation, they usually call off the hounds after a point (either it works, it doesn't, or it is just too much). Hopefully that is the point where you have nuked your way into some new treatment options.
Good luck, I wish I could offer something more helpful. Radiation is insanity. I look back at my generic RC radiation in a haze. For friends ranging from breast, prostate, to brain, their periods of radiation were always trying.
Keep us updated where you can. I have faith that wiser minds than mine will have some productive advice.
DX 11/09 RC Stage IIIb
12/09 Chemorad w/Folfox
Surgery 4/10 LAR, Removed Seminal Vesicles
Clean Margins, T3N2M0, 4/19 Nodes
6/10, 10/10, 1/11 Clean Scans, Normal CEA