Could you fill up this form? That way we can help determine what's wrong with your cham. But that lump should be checked out by a vet even if you decide to take him back to the breeder.
https://www.chameleonforums.com/threads/how-to-ask-for-help.66/
I really recommend doing a bioactive setup. It helps keeping the cage clean and makes draining the water out really easy. Here's a good video on how to do it. This channel also has other great videos on the topic.
I have a bioactive setup myself and have done quite a bit of research so if you...
I recommend wrapping three sides of the cage in a shower cutrain for example. It's fairly easy to do and can be easily removed if necessary. Only downside is that it doesn't look that good :D
And what come to the personality, sometimes chameleons' personality changes. It might be just a growing up thing or could be linked to some mildly traumatic event (a loud noise for example)
I was just wondering do other people give their chameleons a middle name/surname. My little boy has two middle names and a surname :D
Feel free to share if you have given more than one name.