Hello, my name is***** and I have over 20 years of experience as a veterinarian. I am sorry that you have been waiting for a response, but your requested expert isn't online which delayed your question coming up on the list for all to answer. I would like to help if you are still interested in an opinion. I’m sorry to hear that your kitty has a severe case of "pillow foot" (Plasma cell pododermatitis) that does not seem to be responding to cortisone injections.
I understand that you are looking for "natural cures" and depending upon the cause there may be some natural supplements and/or a diet change that could help, but I suspect that we need the proper traditional medication as well.
Traditionally "pillow foot" only affects the pads of the feet. Has he had a biopsy of his affected areas to definitively diagnose his condition? There are other conditions that can have similar symptoms and perhaps a misdiagnosis would explain his lack of response.
Certainly a food allergy can cause itchy feet and excess grooming of the feet and if he grooms enough that could lead to a secondary skin inflammation and an infection. Usually with food allergies we see other areas (the ears, lips, and sometimes the abdomen) also affected, not just the paws. That could explain why he has lesions on his lips too.
If he doesn’t go outside trauma is less likely, although this can be from a burn if he’s a cat that likes to get up on your kitchen counters.
Another possibility is an autoimmune disease (body attacks itself) including plasma cell pododermatitis, pemphigus or vasculitis (inflammation of the small blood vessels) that has led to erosions and ulcers of the skin of his pads and lips. These diseases are diagnosed via a biopsy at his veterinarian. Treatment will depend upon the particular disease but usually involves immunosuppressive doses of steroids and antibiotics to treat any secondary infections. Plasma Cell Pododermatitis and Pemphigus are also somewhat responsive to the use of Doxycycline, an antibiotic that also has anti-inflammatory properties. Below is a picture of a cat’s paws affected by pemphigus foliaceus. The lesions tend to affect multiple paw pads, and have a proliferative, “crusty”appearance:
And below is a picture of a cat with plasma cell pododermatitis. The lesions can affect one paw pad or several at a time, give the pad a “pillow” appearance, and a more dry and cracked than a proliferative appearance:
I would have him rechecked by his veterinarian if you don’t feel that the steroid injections have helped much and possibly adding the antibiotic Doxycycline.
In the meantime try to keep his feet clean, especially after trips to the litter box. You can soak his affected feet in a dilute solution of warm water and antibacterial hand soap and then rinse and pat the paw dry.
You may also wish to start an omega 3 fatty acid supplement as these are natural anti-inflammatories and improve skin health in general. I recommend a dose based upon the EPA portion (eicosapentanoic acid) of the supplement as if we do that the rest of the supplement will be properly balanced. Give him 20mg of EPA per pound of body weight per day. For example an 8 pound cat could take 160mg of EPA per day.
Rarely we can see skin lesions due to a upper respiratory virus, particularly the Herpes virus. That could explain his additional lip lesions too. Or it may be that he is stressed by his paw lesions, which suppressed his immune system and led to other symptoms.
I think at this point a recheck is in order. I think that it would be prudent to check him for immunosuppressive viruses, feline leukemia virus or feline immunodeficiency virus, since his symptoms have lingered. A simple blood test at his veterinarian’s office can be done.
A biopsy of his affected paws could be very helpful in determining a treatment plan as well.
My concern is that we may not be treating properly because we don't have a definitive diagnosis, or that there may be complicating factors we need to address.
Please let me know if you have any questions.