B.,
Welcome to the site. Glad you found it. there are a couple of things from your short post that I can suggest. The black spot is possibly a scab or bruise from your cham rubbing his nose on the screen. Hopefully, you've removed the crickets. What did he "chew" in the corner? There shouldn't be anything for him to chew in the enclosure that isn't food. The open mouth could be from over heating, or possibly a URI, or he maybe just gaping at you. First things first though...Take a look at the care sheet for your veiled. Are you following the sheet to the T? If not, adjust to the proper specs on it. Second, fill out the form in this thread here:
https://www.chameleonforums.com/threads/how-to-ask-for-help.66/
With the following info., we should be able to get a handle on how to help you.