Congratulations! In addition what Christine said, rinsing with non hot liquid tea may help reduce the thick mucus, drinking adequate fluids, taking Mucinex or Robotusm, using a stick sponge or gauze on fingertips to get the mucus around the gums, taking a steam shower, some use a neti pot, but I wasn't going to stick my face in anything, and the water, preferably distilled, needs to be changed, and pot cleaned daily, a humidifier which the same goes for cleaning, gentle patting in the middle back by someone, which I learned in the hospital from a nurse got some gunk out. I may have tried once, but some use steak tenderizer diluted with water to rinse with too.

The thick mucus is from the salivary glands, mainly parotid, which produces mostly think mucus, other two major salivary glands a mixture of thick and thin, but mostly thick, and radiation mainly destroys the thin saliva, not thick, so you're left with the thick saliva until the salivary gland recovers or others compensate for its loss.