If your keeping it, and if its better off with you, then you should be taking it to the vet ASAP, like in the next day or so. For an URI you will probably be giving Batyril injections, and if its really bad, nebulizer treatments.
Are you prepared to do this?
You have other reptiles, quarantine this one or you could be treating them all for this
Vet taken care of, he is ordering Batyril and should come the beginning of the week. Hopefully its not viral cause then it would just be a waste of time sad to say..