Alicia,
If the frog has left over shed on him, the enclosure is not humid enough. It's really as simple as that
Spray more ! Most hygrometers on the market are not reliable, and in fact probably..... useless. Ignore it

The frog's shed should be very slimy looking.

I had a few hygrometers that never moved from 90%.. I tossed them !!!!!

Another hint that the humidity is too low is to observe your forg.
He may hide and stay in the dampest areas of the enclosure.

Does the frog have a source of water in the tank.... ie a dish he can sit in?