dark mark

[Elisha]

I brought my panther chameleon to school for the first time, he is about 6 months and I am a teacher. I had a few students hold him, and I fed him 4 worms. I had him in a little plastic bird cage, and I've done this before with my veiled chameleon and never had any problems. I had him at school for about 2 hours when he started developing a dark, almost swollen spot on his side. I took him home into his tank immediately. It didn't seem to be sore the the touch, and seems almost to be blister - like and I'm worried he got to close to the light I set up and burnt himself, or fell. I went to check on him about an hour later, and the spot is still there, but now almost lighter than him. It is circular. Any advice? I'm extremely worried!