Hi Justin,
Since I was one who helped to hijack your thread I apologize. You had a serious problem and we turned it into a lesson in Lepidoptera ;(
There is an article on ChamNews all about what to expect from a vet visit. I hope you are bringing a fresh fecal for him to check. If he is not pooping regularly you could try to give him a warm soak to get it out of him. Remove from any water right away (the poop) and put in glass jar.
If he is dehydrated (probably is if he has not been drinking) the vet may want to give him subcutaneous fluids. I would use pedialyte rather than gatorade (It think it was discussed once and that gatorade has extra sugar in it that are not needed by your cham. But generic brand pedialyte and keep in fridge. it does not keep more than a few days. Ask me after you get back and I will dig up the recipe for home made so you can make as much or as little as you need (or freeze like Carlton suggested).
I am curious - since you have had him for a long time did you see any signs earlier (looking back, now). This is not to judge you, we ALL know how hard it is to see things coming sometimes and even with the best and most attentive care things happen (Luna was doing better than in a long time and something burst and I lost her in a matter of hours).
You may have gotten comfortable with his setup and figured all was OK, but just for a refresher you might want to post your setup specifics (see link below and go to Setup Questions section) and we can look it over with a fresh eyes.
Let us know how things go and I hope you come back with good news! Here is a link to the article
lele
Vet visit
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Chameleon Help & Resource Info
0.1 Veiled Chameleon - Luna. She's now hanging from her big jungle gym in the sky
1.0 Beardie - Darwin
0.2 felines - Kyndra and Lita
0.1 African Clawed Frog - Skipper
0.1 Mad. Hissers and she is on the loose!
0.1 Chilean Rose Hair Tarantula - Rosa Leigh
0.1 Goliath Bird-Eater Tarantula - Natasha
?.? Pinktoe Tarantula - no name yet