Thanks for your help!! Hmm, I have not tried lysine but can give that a go. Our vet said it wouldn't be feline herpes BECAUSE the sores were around his mouth?? I just googled a bit and read that rodent ulcers are common in cats with feline leukemia, and did find a photo of what his chin has...
My cat is about 8 years old now, and this has been happening since he was around 4 or 5. His face will swell in different areas, usually around the mouth and lips but sometimes it is very different and really changes his facial appearance.
I have seen the vet a few times, and switched around to...