Chronic diseases are much more difficult to treat than acute infectious diseases, and sometimes can only be managed and not cured. The correct thing to do would be to stop vaccinating, and stabilize the immune system before proceeding. I have seen some animals where the immune system was devastated by the first ever puppy or kitten shot, and they could not be safely revaccinated. What to do? You could check antibody titers to see whether they have attained immunity. You should restore the health and integrity of the immune system. This is achieved with diet, nutrition, and homeopathic remedies.