sore on lip

Question

lilly lip   Hello, I'm writing to ask about a sore my cat has. It's on her upper lip and part of her nose. It's very localized, just the upper lip on one side. It's sort of raw looking and just looks inflamed.
It doesn't seem to be bothering her at all, she's eating, drinking, playing. It almost appears to be coming from her gums.
She's had it before, but I just waited it out and it actually cleared up.
SHe does not tolerate vet visits, and has to be sedated to even take her out of her carrier.
I do have another kitten, almost a year old, she has no issues.
My Lilly is 5 years old.
I've been cleaning the water bowls and food dishes more frequently.
I was hoping to get some advice on how I might treat it, or if I should take her to the vet despite the stress it induces for her.
She's an orange tabby, spayed, has never been outside, no other animals or children.
I am a nurse midwife, so I have some medical/herbal knowledge, if I can describe it better or another pic would help, just let me know.

Thanks, I appreciate your time!
SHelley

Answer
This looks like something called a "rodent ulcer" which is part of the eosinophilic granuloma complex. That is usually attributed to some type of allergic reaction.  The treatment for this is a shot of a long acting steroid called DepoMedrol or an oral drug called Atopica for Cats.