I'm 6 month post treatment for stage IV tonsil / HPV related. Thirty five radiation treatments and 7 cisplatin treatments/no surgery. After complaining about what I thought was mucus, a nurse told me it may well be the viscosity of my saliva and not mucus. I'm not sure if it's mucus or thick saliva.... but mouth moisturizing sprays have provided temp relief - particularly, for me, Thayers mouth spray available via web