Hi Winnart! I don’t know if I will be of much help, but I do have a suggestion. If you do not agree with what the vet’s office had stated, regarding you cat & since they do not know what the problem is. I would call a 24-hour animal hospital & tell them what the problem is. Tell them it would have to be an open appt. When your cat swells up again, you want to bring him in immediately!! Have their their veterinarians look at him. Even if this means, leaving him there for a day or two, so they can examine him & watch him. I will have your cat in my prayers, that this condition will not appear again. Please keep us informed.