Classic signs of an upper respiratory infection. Vet visit is the only way to ensure she is treated properly. Most bad upper respiratory infections require antibiotics which only a vet experienced with reptiles can subscribe.
Respiratory infections in dragons tend to be caused by too high humidity or unclean/too cold conditions in the cage. Get another digital thermometer, and hydrometer. double check your setup to make sure the cool and warm temps are in the right range and the basking temp is high enough. Make sure the humidity isn't above 50%. If humidity is too high, increase ventilation into the cage or, if your home humidity is too high, get a dehumidifier for the room your dragon is in.
Hot basking lights tend to dry out the air in dragon cages, so it may be needed to reduce ventilation to allow the lights to evaporate the humidity. remove large water bowls from the cage if you have them. Molds etc can also irritate and cause lung problems for dragons if they are exposed to them to much. Improper substrates can also retain humidity, such as any wood shavings which shouldn't be used with dragons at all. Newspaper, paper towel are find.
Changing the cage conditions for your dragon won't cure him, but it will definitely help prevent future occurrences of URI in your dragon.
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PHLdyPayne