Hmph. I just wrote about allergies not long ago and I realise that Slinky is having one. It is concentrated under her chin, and is in the form of small pustules.
The area is under her chin so I reckon it is contact from food of some kind. The only thing different that she has been eating lately is crab meat in their canned food, so I reckon she is actually allergic to the contact from crab meat. I don’t usually give them this flavour of food, sticking to the tuna and chicken flavour mostly, but we got it as a gift from Aswat to help offset our feeding costs when we were fostering Tikkie.
Her allergy is quite unique in that it is only concentrated on her chin, which means that it is a contact allergy primarily. But because it is around her mouth it is most likely something she is digging her face into that is causing the contact allergy, hence the conclusion that it is the crab meat.
Stopping her consumption of the crab-and-tuna food, as well as applying antiseptic on her chin to help it heal. She has scratched it and one of the pustules is bleeding. Poor Slinks.