Is this an adult, juvenile, or hatchling? What are the temperatures? Was it in good weight before the illness, and how long has it gone without food? If it was a heavy juvenile or adult before becoming ill, it could go a week or two easily without eating. Keep the water shallow, but make sure it is drinking/soaking often enough. Put it in the water 1x or 2x daily if you suspect he's not getting in himself.

It never hurts to have a vet do a culture of the discharge, if your wallet can take the hit.

Katrina
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1.2 Eastern Muds - Fred, Ethel, Edith
0.1 Iguana - Tiffel
0.1 Bearded Dragon - Foster
Foster turtles: More than I'd like the husband to know about.