I remember this little fella and his troubles.
Poor little jacksons.
Interesting that the vet is thinking that the temps were too low.
They can easily make it past the 50ºF overnight temps.
The mountain forests where they're found gets pretty cold and misty.
While I can't rule out a parasitic infection of some sort I really doubt that either some worm's or gout. - Many cases of gout seem to be caused by high phosphorus levels in some supplements and over supplementation by concerned owners.
Re: supplements are you using...
I'm thinking that the herptivite can be cut down to once every few weeks to month as he's full grown now.
What I'm thinking is that right off the bat ... he's got some sharp nails and that he's digging into the ficus and causing the latex to bleed.
Ficus latex is pretty irritating and can lead to an allergenic reaction
That could explain both the discoloration and the swelling.
So lets try getting rid of that ficus tree in there and see if we can find something else better suited for his habitat.
From our PM conversation that I haven't responded too yet.
Please remove the 10.0 UV light. It's too powerful and that unless you have it far away it can cause skin burns and blindness. Right now he's got a pretty well filled cage and is going to be too exposed to that UV source when he's trying to warm himself up.
A 5.0 is more than enough for these animals... set right on top of the screencage.
Boiling the plastic isn't going to help detoxify it.
You can use a hydrogen peroxide and bleach solution to clean them with... but my preference is to remove the plastic all together and use some of the bendable fake vines. They're easier on the feet and aren't something that they'll want to lick off of. Licking of plastic leaves can help bacteria colonies to form and that can cause it's own problems.
Lets slow down on the misting... all of my jacksons took to drinking out of glasses soon after I got them with no problem. If you feel that syringing is working then please continue.
Unless your indoor temps are getting down into the low 50ºF range I would not use such a strong heat lamp overnight.
70ºF is a decent temp for these. If yours is sourced from Hawaii then it can handle the higher temps... but keeping them below 85ºF is advisable.
Hope that this helps :D