I'd take Charlie to the vet for full blood work and x-rays to rule out any medical issues. Inexplicable aggression like that can be a sign of pain. Not to scare you, but our 12-year-old male, Drago, was diagnosed with an inoperable liver tumor in July 2014 (he was euthanized during surgery, and the results came back as bile duct cancer). By the time it was caught, the tumor was the size of a softball and there was no healthy liver tissue left (thus the decision to euthanize). He was a really large male, but I still couldn't fathom how something like that fit inside him and went undetected for as long as it took to grow that big.
It sucks because we just don't know what's going on and can only rely on the experience of other owners and veterinarians (who also rely on owners taking their iguana to them for examination to learn about these things).
Wishing you and Charlie the best, and I hope you are able to find out what's going on.
Mindy and Oggie
RIP Reno, Paquita and Drago