Possible Respiratory Infection (help)

Hello,
I have a 6.5-year-old bearded dragon that all of sudden started to have a wet cough, difficulty in breathing, black beard, and became white from above. I read and found out that is possible to have a respiratory infection. So I follow what information I found on the internet: I increased the temperature in her cage, feed her with a syringe, and reduce the humidity; yet the night she started to show signs that she is suffering from pain. Very bad cough, run-amok in the terrarium, and at the end she hit her head with power on her things and the glass. And then she fell asleep I thought that she was dying, with half-open eyes and no response for ten or so minutes, then she woke up again, (very painful to see her suffering like that). Today is a little better but still, she is coughing a lot, I feed her again, but I don’t know what to do. The vets in my area will be available from Tuesday since here is a holiday time and there isn’t any vet open that can handle a reptile.
The last two weeks she didn’t have a lot of appetites, but it happens from time to time. She was pooping and everything was normal until a few days ago. Also, I didn’t bathe her or change anything in her food or the temperature in her terrarium.

Thank you.

Please post a pic of her and tell us what your using for a UVB brand and bulb coil or tube and where in the tank its at --- basking temps and how are you taking them NO stick ons please --- any colored bulbs in the tank ?

For UVB I’m using bulb coil, the ones that labeled as 10% or desert and there is directly from above on the basking area, close to the heating lamp, which is zoomed sun light: 100watt, 60watt, or 30watt (depends on the season.) I’m using the companies exo-terra, zoomed, and Trixie for UVB, based on what I can found when the time is to change the lamb (around 6-8 months). I don’t use any lamb with color.
For the temperature, I have always an analogy thermometer in the middle of the tank which is around 32-34c at the basking area is 36-38c (sometimes 40c when is a very hot day) and on the cool area around 29c. The measures are taken by a classic analog thermometer which I only put inside to check the basking area and the cool area once in a while. (The basic thermometer that is in the middle is always there). At night the temperature is always above 22c.

https://imgur.com/a/o8Pbn4V

Please get rid of the coil bulb --- for tanks that are 40+ gallon they are inadequate and in my opinion they are inadequate in any tank --- they cause all kinds of health issues because they do not emit enough UVB for the dragon --- please get a Arcadia Pro T 5 for a fixture w / a Arcadia 12% here is a link
https://www.reptiles.swelluk.com/arcadia-prot5-kit-desert-12/
You want to order this or get one ASAP---
Also you need to get a digital probe thermometer for accurate basking temps- analogs are good for ambient temps ONLY --- the probe will give you an exact temp it needs to be placed where he sits for basking -- does he have any mucous or drainage out of his nose or mouth any clicking noises when he breaths - any breathing out of the mouth?
When you get the UVB replaced please post back on here and we can help you get it set up in the tank -- they require certain distance and placement to be effective

Doesn’t have any mucous or drainage on her mouth or nose nor any clicking noises. Only once she “throw out” some mucous but nothing since then. She is taking deep breathes with an open mouth once in a while though but without clicking sound is more like a noisy hissing.
I will look at the uvb that you recommend, and I will change it.