Did the vet give you antibiotics for this infection? My girl has one just now and we are on baytril every day for 2 weeks, however, every case is different so don't assume you're not getting the right treatment!
We have raised her temperatures about 5-10 degrees farenheit to help combat the infection. Chameleons don't produce a fever like we do so I'm hoping it will help things along.
Also we are taking her into the steamy bathroom every second day. We pretty much just let the shower run really hot (whith our cham at the other side of the bathroom to be safe) and put her on a big fake tree in there for 1 hour at a time. This is so that we can get her to breathe in the warm steam which should help clear mucus from her airways.
We have been doing these things since the start of this week and I have to say she is looking and acting a bit better! We still have just over a week to go.
If you do have baytril, it's really important to offer your chameleon a bit more water. Yes too much humidity constantly can contribute to an infection, but antibiotics can put them off food and dehydrate them so if he is on any, you will need to offer him LOTS to drink.