Sounds like an upper respiratory problem. I would take it to a vet asap and have them run a culture. I would keep it warm and maybe humid until than since that sometimes helps. But since it is a desert species do not take my word on the humidity. If it still persists for a few days take it to a vet!!!

I have had many tortoises with respiratory problems and it usually takes antibiotics to cure them. Once in a while heating them up works but it is rare. If you do not want to give it injections you could try administering the antibiotic with a nebulizer hooked up to a rubbermaid with the tortoise in it. I have had some success with this system for respiratory problems.

Good luck!

Marc P