Itchy lips

Hello, I have been using my CPAP for probably 2.5 years now. Lately, the past several months, I get itchy, almost swollen lips at times. At first I thought it was a food reaction. But after trying to weed certain things out, there's no link to any certain foods I eat. A dermatologist did some cultures which came back negative. Gave a steroid cream to use periodically, but said I shouldn't use it often. I use a full face mask, and never had any real problems before this. I almost wonder if it could be fungal??? Like my lips are staying too moist? I do use a special lip balm the dermatologist gave me, which I really like. Anyone have any thoughts or similar experiences?

No experience with it but find it interesting. Have you tried using a mask liner to see if avoiding skin contact makes any difference?

Return to the doctor--ask for an anesthetic lip balm.
Itching often works into a loop, and stopping the itch, even for a bit, stops the cycle.
A steroid works by reducing inflammation. It does nothing for a nerve malfunction.
When I have an itch that does not respond to cortisone, I get out the Neosporin pain relief,
(When location allows. --not near eyes, etc.)