My cat is 10 years old and for aaages now she has had blue rings which are around four of her nipples,

the vets are baffled by it and so is everyone else who has had cats. She also has a very bad infection due to her allergy to fleas, which has left her with swollen glands on her lower abdomen, this is being treated by steroids and penicillin but they aren't decreasing in size. The vets aren't doing anything more about her swollen lumps and are concentrating on her allergy to fleas instead.
Has anyone ever seen this on a cat before? Does anyone know anything about her condition, please get in touch if you do.
Many Thanks.