Cat uri?

Hi! We just got a new male cat (3-5) from the shelter yesterday. He was a little sneezy yesterday and when we woke up this morning we noticed he had a runny nose. As the day has gone on he has started to have nasal discharge and clear eye discharge. He also has some trouble breathing and whistles. He’s very lethargic and hides under the couch but that could also be due to the new environment. Is this enough to take him to the vet or will it fade on its own?