I had to treat a graybanded kingsnake for stomatitis once. He developed it as a secondary result of a respiratory ailment. The big question when a snake gets stomatitis is why? Often there is an underlying cause and it is often a secondary infection, not the primary one. Watch the snake closely for other signs of ailment, especially respiratory. One possibility though is if they get a piece of substrate stuck in their mouth, and it sits in there, that introduces bacteria and can cause an infection all on it's own. The swelling on either side of the face as you have described actually sounds like something a little different... blockage of a duct that connects between the eye and the mouth... which can lead to both mouth infections and eye infections as well. From what I learned through a vet there is a duct that kind of allows some drainage to go between the eye and the mouth and if this gets blocked off by foreign material or mucous or bacteria or WHATEVER it can cause the eye to swell and fill with milky fluid and can also cause mouth infection. I learned all of this when I had a female concinnus who first had a swollen side of the lip under her eye and then they eye proceeded to cloud and swell. I would open the snake's mouth and search for a cottage-cheese looking material, and of course blood/obvious signs of trauma. If you see this you know you have mouth rot... I successfully treated my case of the graybanded king with a dilute peroxide solution. The snake wasn't too happy about having his mouth peroxided several times a day but it cleared up very quickly and saved his life. The female concinnus with the eye problem eventually died despite the antibiotics and treatment.