Mouth ulcers. I hate them.

Usually they show up when I've been breathing through my mouth all night because my nose is clogged.  Possible prevention: nasal spray at bedtime and a decongestant.  Maybe my new CPAP will keep me humidified (I didn't wear it with a clogged nose, it felt too much like I couldn't breathe).  Officially nobody mentions this as a cause... sources mention damage, hormones, genetics, SLS in toothpaste, a billion other things, but the obvious cause in my case (almost every time) is dry mouth from night-breathing by mouth. Why is this never listed as a cause? Am I really that unique?