Herbert is about a year old now and still has that yellow spot on his side, so I decided to take him to the vet for a checkup. I searched the list of reptile vets in Pennsylvania and found one a couple miles away. He also used to live a couple houses down the street from the house I grew up in, so I already knew who he was.
Herbert weighs 123 grams and appears to be perfectly healthy, other than the yellow spot on his side. The vet said that he has seen a few chameleons over the years, but not any with abnormal skin growths. I was a little disappointed that I knew more about chameleon diseases, fungal infections, and viruses than he did (thanks to this awesome forum and all of its knowledgeable members). He had never heard of papilloma in chameleons and searched his national medical database for cases, pictures, and treatment options. To make a long story short, he had no idea what it is and said the only way to accurately identify it is to do a skin biopsy.
So Herbert goes back early September and they are going to take a circular chunk of skin out of him, give him a stitch or two, and then send the sample to a lab where they will hopefully be able to identify the problem. It'll cost about $250 (which is 4 times as much as we paid for him as baby). But we love him and want to confirm what it is and start treatment if possible, or confirm my worst fear that it is an untreatable virus and we'll continue to give him the best life that we can.
Since starting this thread, I've noticed another abnormal spot that appeared on the same side

Here is a picture of the first initial spot.
Here is a photo of the new spot that I found on him. It is a raised cluster of skin (it's a lot easier to notice in real life compared to this photo)
Can anyone out there identify either of these spots and offer some advice? It would be greatly appreciated whether the news is good or bad. I would just like to know what we're dealing with in case there are any treatment options. Thanks.
-Craig and Herbert