Okay. I took him to the vet today. He told me that it definitely sounded like an upper respiratory infection. He took some x-rays but the lungs looked clean! Then he called another vet who said it could also be lungworm but they would also have shown up on the xrays.

Worried about the possibility of pnemonia he said I should lower his heat, raise his humidity, change his substrate and watch him until Thursday. If the symptoms don't subside by then I'm supposed to take him back in.