I don't know if you have figured out how to help your cat with the constantly running nose, but I had a kitty just like that. She contracted a URI when she was 10 days old and I had to go to heroic lengths to keep her alive. She grew up to be a very happy cat but she too had constant either white, yellow, greenish-brown snot coming out of her nose (never clear) and the vets told me that it could last her whole life due to the fact that she had contracted the herpes virus at such a young age. I tried various antibiotics, Llysine, even something they give people for herpes (all prescribed by my vet) but none of it worked well, if at all. Then I got very lucky----I saw a cat osteopath who recommended something that completely took away the snot so long as I treated her every day: and that was bovine colostrum, otherwise known as the stuff a mother cow secrets just after she's had a calf, before the milk comes. It's packed with things to boost the immune system. The Dr. recommended using colostrum from New Zealand, as new Zealand cows are less stressed and graze in open fields. If you go on Amazon you just type in New Zealand colostrum and several choices will come up. It comes in a powder form, I mixed it up with water and put it in a syringe and tried to give her 40 cc's a day. The more I could get down her, the better. She sometimes liked the taste, and sometimes not but it was A LOT easier than trying to get any of the other options into her. Most animals apparently love the taste. It was so wonderful to be able to see her enjoying being a normal cat at last. I kept her on this for 2 years, it worked the whole time, and then she ran away.... that part sucks. Anyway, if you have tried everything else and aren't satisfied with the results you've gotten, I think this is the best stuff out there for this problem.