Jpf about the black marks. When chameleons are scratched or rub against things they may form black marks which I believe to be some sort of bruising of the skin. It is likely the chameleon rubbed it's nose against the mesh or even on a branch.
There are several things that don't seem right with your caging such as lighting and plants - which are essential. You should fill out the how to ask for help form above posted by Camryn. I think there may be some things we can point out to you that can make your chameleon keeping as trouble free as possible. These sort of things, if not corrected, can lead to the premature death of your chameleon. I hope you can find the time to fill it out, as soon as possible.