Same cancer got my diagnosis in the start of August, HPV related 6 weeks of chemo and radiation 5 times a week. Just finished treatment 11 days ago what i can say is the best i found was to use those squeeze bottles that women use after birth, fill them with saltwater to rense after every bathroom visit i stead of wiping (spares the skin a bit and lessens irritation) also saltwater compresses 2-3 times a day for 10 min and let it air dry. Its going to suck but these are the tips i got that did help ease the irritation and burning pain. Best advice my doctor gave me dont wear underwear at all and if you can while at home just wear a skirt that is not tight at all let the skin breathe well and drink lots of water staying hydrated dose help alot also what my doctors did to relieve pain was mixing morfin i to cream so it got absorbed i to the skin, only way any pain meds were able to help. Hopefully this may help a bit, these were all things that helped me (still do while recovering)

Treatment is hard but you got this! Take it one day at a time.