Typically it is cooler temps that can cause respiratory issues, but low humidity is probably the second most common cause. With cage temps as high as you are stating, even if just the hot spot, your interior cage humidity is most likely extremely low. This dries and damages lung tissue and can cause irritation and possible infections. Raise the interior cage humidity up to between 70% and 80% and lower your hot spot down to 90 for now and see if that helps any.

Also, chemical exposure in the air within the cage can cause these symptoms as well. Has there been any exposure of this type lately?

Kelly