Welcome to the forum. It can definitely be stressful when your Chams not doing well. Not eating and sleeping during the day do sound like signs of stress
@Beman is great helping new keepers and has given great advice.
I think two things are important to hopefully helping your little get better. Ensuring proper environmental conditions and treating any acute illness. Beman and others can help with the enclosure, but she’ll likely need to see a veterinarian with reptile experience very soon.
Is she holding her nose in air?
Is she still moving normally, or does she have difficulty holding up her own weight, falling?
she will eventually need a larger enclosure, but in her current one you want to create gradients of heat, UVB, humidity and exposure
As already mentioned, a thermometer with a probe at her basking area is important so you can monitor her basking temps. Low 80s should be the maximum temps for her basking spot and you can raise her basking bulb or reduce the wattage to achieve this
A T5HO UVB bulb should provide plenty of UVB light for her. In this smaller enclosure you might consider raising the fixture a few inches above the enclosure
as noted your daytime humidity is a little too high. I have a couple of glass enclosures as well, and I need to use fans on timers during the day to lower daytime humidity. I am using a small computer fan currently and it works well. Nighttime humidity above 75-80% is great for them.
the last is exposure. Lots of branches so she can access all levels of the cage. In this size enclosure, an upper level in the top third and some in the middle the lower third. And more importantly, live plants creating areas she can totally hide away from being seen and from the heat and UVB light
nutrition through feeder variety (as much different appropriately sized bugs as you can find, variety in feeding/gutloading of the bugs and proper supplementation that Beman has also addressed