She doesn't look good.
Fortaz is a good broad-spectrum antibiotic that I use quite often (although it's been on backorder for the last 8 months now - making me crazy!) but reptiles get sick very slowly and they heal very slowly. If she has gone several weeks without eating at her age I would consider getting some nutrition into her. One way is to place a stunned cricket (I just kind of squish their head enough that they are stunned but not dead) and place it in her mouth. Ideally she will swallow it once it's in her mouth. The other option is a liquid diet like carnivore care that can be used for short term nutrition. It's ideal if she'll drink it like water (see below on how to safely do that) because otherwise you can to squirt it slowly into the mouth and aspiration is a risk. It takes practice and finesse to be comfortable with it. I would definitely try to get some food in her though. An adult I wouldn't be as worried about not eating for a few weeks but at her age she's not going to be strong enough to fight without nutrients. 2 weeks without visual progress isn't all that unusual in the chameleon world honestly. Hopefully some nutrients will help her turn that corner. The addition of a second antibiotic may increase the coverage for bacteria but unfortunately it may be dually harder on her already weakened body.
When offering water the best way to do it is drip it into her mouth as she's drinking. A lot of chameleons can be stimulated to drink this way when you bring the water to them. This is the safest option because then she is drinking like normal so you really don't have to worry about her aspirating because it's on her terms. If you are squirting it directly into the mouth that's when you have more risks. So what I usually do if they're not wanting to drink is open their mouth to put a drop or two in and then they start licking so I drip it on their nose until they're done licking it up. A shower session may also be beneficial.
https://www.chameleonforums.com/blogs/entry/shower-sessions-for-hydration.732/
Your humidity is fine as long the cage can dry out between mistings so the 70-80% should be the peak and then it should decrease to closer to 50-60%. If there is any standing water that is concerning. If there is any mold or growth under pots or on any cage decor that is very worrisome. Sometimes it happens in the joints of the cage itself. But most of the time if there is good air flow and no standing water this is rarely a problem.
Temperature of 85 is also appropriate and can even go up to 90 to help her immune system fight it off as long as she's not too close to the light and can potentially move away from it if needed. Less than 85 is potentially more harmful as her metabolism will slow and thus her immune system as well. Night temperatures in the 60s should not be a problem at all. In fact a night temperature drop is preferred. So this most likely did not contribute.
So right now I'd focus on keeping her warm safely and trying to get some nutrition and hydration in her while reducing stress as much as possible (even though those are somewhat counter intuitive).
