You should have been to a vet a long time ago... And i agree with Syn, you obviously didn't look like someone who was planning to go to a vet in the very short term.
No expert will take a risk on saying what it is, because you provided a very small resolution picture, because it can be a wide variety of pathology, and because we barely know anything about the conditions your chameleon is kept in.
The only good suggestion for you is the one that has been mentionned a good number of time: VET ASAP. Not next week, not in 4 days, TOMORROW max. Your chameleon should have seen a vet a week and a half ago, if not two weeks ago.
Now if you want a second opinion, once you have seen your vet, please fill the Help Form like BridgoFaith suggested and we might be able to tell you more.
PS: No matter what we can tell you here, i doubt there is anything you can do to help your chameleon unless you see a real and specialized vet. Your chameleon will most likely need a minor surgery and some prescription too, not to say a good review of your whole setup.