In the time I have had keeping chameleons, bugs such as crickets or roaches always gather in the top corners/edges of the cage. Ive found it's pretty rare to see feeders that will stay in the lower half of the cage.
As a juvenile your veiled should do fine in that cage. As an adult however you need something at least 24x24x48 in.
It's not good to keep a chameleon in an all glass enclosure. Maybe try to make him a cheap little temporary mesh cage. (pvc frame, plastic garden mesh, zip ties...)
Actually keeping him in his adult cage already would be fine as long as you cup feed him, so he is able to find his food.
You can also just raise the pvc base tray to make the cage smaller...
What you have described are all symptoms of URI aka upper respiratory infection. Tomorrow check her mouth and find out whether or not she has a thick mucus inside.