Sandra - no idea if this is helpful, but chamnews has a very graphic set of photos from a necropsy - at least it will show where everything is located. It shows a variety of species and variety of ailments, etc.
I have a friend in FL who had a very large panther (don't recall species) that was wild caught and had a rough few first 3 years. He was 7 or 8 when she lost him last year. I met him in 2003(?) and you could see his arthritis setting in and he was getting around a bit slower. I think your guy is just getting old and sometimes it's better not knowing, especially if nothing could be done now. Just keep giving him all the lovin' you obviously have been 
lele
necropsy
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Chameleon Help & Resource Info
1.0 Nosy Be Panther Chameleon - Cyrus
0.1 Veiled Chameleon - Luna. She's now hanging from her big jungle gym in the sky
1.0 Beardie - Darwin
1.1.1 Side-blotched lizards - Ana and Stan
0.2 felines - Kyndra and Lita
0.1 African Clawed Frog - Skippy
0.1 Chilean Rose Hair Tarantula - Rosa Leigh, Died 4/21/06 
0.1 Goliath Bird-Eater Tarantula - Natasha, donated to science 4/4/06
?.? Pinktoe Tarantula - no name yet