I believe this is a hypersensitivity to yeast/fungus. Perhaps a conjunction of a viral plus yeast. I have encountered this myself in the aggressive form of candida. Most O blood types have this genetic problem although I have seem this as well in people after vaccinations, also a few military personnel that encountered toxins while overseas which put some of their system in temp and permanent acidic ph's.
In addition to treating the surface try do a hard-core candida cleanse and stick to an alkaline, low-sugar diet, (avoid stress situations), and that will help avoid problem flare-ups.