I think he might be experiencing heat stress. He is young and still learning to regulate his temperature.
85-86 I think is too hot. The temperature should be around 75-78 F for the basking spot and an ambient temperature of about 70-73 should be fine.
I dont think putting the temp up to 90 will do anymore good for him.
The UVB you are using might also be to strong, for panthers I recommend the 5.0 not 10.0.
The 100watt basking bulb I think is maybe too strong aswell, try a 50-75 watt.
What colours is he displaying now?
If he can also see other reptiles or animals that might freak him out aswell.
I hope he gets better soon.
Incorrect information.
If at anytime while offering advice as to how to keep an animal, you feel the need to use "I think" in a post in which you intend to tell someone what to do, your better off not posting. Not being rude mate, just frank.
For a juvenile panther, 85-86 degrees F. is perfect for basking.
You don't know the posters location, you need to know this before you tell him proper wattages for his setups. Nor do you know the material of the cage he is using (screen, mesh, glass) and thus should not be commenting on what UVB light to use either. Rather you should gather this information first, before making assumptions and passing out false or inapplicable information.
The same applies to Cantgetagoodsn, think and ask before you starting giving directions.
As to the original poster, what makes you think he has a URI? and what is you reasoning for raising the temps?
If you listen closely, does the animal make heavy noises while breathing? or do you hear a popping sound when it opens/closes its mouth? If not then the animal most likely does not have a URI. I only suggest raising the temperatures that high during sickness, and not for extended periods of time.
Without pictures I only can only make assumptions (not recommendations) as to what happened.
A. Crickets nibbled on him during the night and he is upset
B. He felt scared by your presence and tried to defend himself
C. he is entering the "tough guy" stage of development *aka chameleon puberty* and is trying to assert dominance.
S.F