I think you mean he's climbing the screen? Is he a kitten? Mine did that when they were little although I tried to discourage it. They did grow out of it but in the meantime I'd make sure they are really secure.
Sounds like he probably has an abcess. If so, it can be quite serious if it's not treated so I'd bring him into the vet right away. The longer it's let go the worse (and more expensive) it can get.
Good luck and let us know how he's doing.