Please post a pic of your set up. It sounds like a fish tank to me, which would be inadequate. Do not leave uneaten crickets in the cage. They can bite your chameleon and cause him harm. PLEASE read the caresheet the other member attached for you and make the necessary changes. A healthy 3 month old chameleon should be eating about 20 small crickets or feeders a day. Your cage is TOO cold. He may not be able to digest his food properly. You need to get a basking temp in the 85 degree range and the rest of the cage should have about a 10 degree temp drop. The caresheet will tell you everything you need to buy and what you need to do to keep your chameleon healthy. If you keep him in the current conditions, he will not thrive. I just realized you posted another thread about him sleeping and I commented on that. Yes, you are using a fish tank and that really is not suitable for housing.