Upper Respiratory infection Recovery/ sneezing?

[ILoveMYCatChip]

I adopted my cat chip in October shortly after his health was on a sharp decline after being exposed to a virus that led to an upper respiratory infection. He did not eat and got super skinny, severely dehydrated. He was on the brink of death! I had to give him back to his foster mom so she can take care of him while I'm at work, since she works at the shelter. He had copious amounts of bright green nasal discharge and lots of sneezing. He was given antibiotics, tested negative for worms, feline leukemia and feline herpes. He is doing much better now, he is chubby, big, playful and always hungry! But, he still sneezes often and gets brown crust on his nose, since these boogers are brown I assume they are old boogers being pushed up his nose from when he had the infection. He recently started sneezing often, he has had no interaction with any other cats. It is winter over here and he never goes outside so that makes the allergies theory skim. I give him tomylin nutritional powder and recently bought him this L-lysine gel. I think they are building up his immune system but only suppressing his symptoms. He eats blue buffalo kitten dry food and fancy feast, sometimes a can of tuna. Can someone provide help? Thank you.
These are his supplements:

 

[ILoveMYCatChip]

I also give him pet safe cbd oil to help with his immune system and anxiety

 

[fionasmom]

Fiona herself, along with another of my cats named Kate, had a respiratory infection when I rescued them. They were not the same age and not rescued together. Fiona had a runny eye for the rest of her life. We went to the vet repeatedly but it never resolved, but never bothered her either and I kept the skin clean and healthy. I was told that there can be residual effects from URIs which are ongoing.

The other girl was clearly sick when I rescued her and was isolated outside in a very large and safe dog crate for two weeks. She was treated and while it lingered, she was finally over it....we thought. The vet cleared her to be introduced to the indoor family and she passed it on to most of them, my point being that my experience has been that this infections can really linger. I have used the Viralys.

I only use supplements as secondary treatment after medical advice has been sought, but that is just me. Can you call the vet and ask what might be going on or take your cat in for a visit? He might need another round of antibiotics. Neither of my girls, or the boys who were infected later, looked sick except for the URI. They were eating, good weight, using litter box, etc.