Those dial humidity gauges are notoriously inaccurate. A digital one is better. Having a live plant in the enclosure will help keep the humidity up. The water won't evaporate off the leaves as quickly, so the baby will have longer drinking opportunities. Also, sometimes they drink by lapping up the fine mist of a spray--if you see your baby opening and closing his mouth when you are spraying, he is drinking so keep misting but don't overwhelm him.
I think keeping this baby alive is going to be a challenge. I really hate to say that to you. This should be a time of joy for you, not a time for worrying, but I think worrying and fussing is appropriate based on the tiny size.
I'm glad you've got a glass terrarium which will make it easier to keep the humidity up. The biggest down side of a glass terrarium, especially for such a tiny baby, is heat regulation. Heat can build up in an enclosed space, and I bet your tank is only 18 to 24 inches tall. Babies are not the best at thermoregulating--they might not know to go to the bottom of the cage to get cooler. Also, babies are so tiny, that their temperature fluctuates a lot more quickly than a larger massed animal. I suggest you have many different thermometers at the different levels. I sometimes put in those digital outdoor window thermometers that have a suction cup (made by AcuRite) in cages. If you put in two--one at the bottom and one close to the hottest part but not directly under a heat source--you will be able to monitor the heat.
I like the Repashy superfine calcium. There really is a huge difference between Repashy's calcium and any other. You don't want to have your feeders so coated in calcium they are "ghosts."
I know three crickets a day is not enough at all. Do you have small enough crickets?
Right now, I have a little stunted baby that I am trying to keep alive. He was hatched with problems which yours wasn't, but I wanted to give you an idea of what I do with him so you can get a bit of an understanding of how to treat/feed your baby. My little runty guy is in his own cage, quite a small one compared to yours. Last I weighed him he was 1.3g. Attached is a picture of him on my finger (with a clutch mate behind to give a reference of how runty he really is) so you can judge how big your baby is compared to my 1.3g runt. I put in about 50 or so calcium dusted fruit flies at least once a day and anytime this cage seems to not have many. His cage is only about 5" wide by something like 18" tall and deep. It is a tiny cage compared to your cage, so he has easy access to his food. I also feed him 1/8" crickets which are pretty close in size to the fruit flies (hydei, a large flightless fruit fly). I have very tiny silk worms I've seen him eat. At least once a day, I put in about 20 tiny calcium-dusted crickets. My little runt has a lot of tiny branches filling his cage so he can easily move anywhere. I have areas where he can get away from the UVB lighting.
The stunted baby's siblings are housed together in a much bigger cage that is quite packed with twiggy branches with a few fake plants around for cover and to collect water for drinking. They are offered 1/4" crickets and also fruit flies and silk worms. I don't count how many I put in--I just look at the density of food and add several times a day. I am careful to keep the cricket density low at night in case they bite the babies. I make sure my crickets are really well fed and I think that helps prevent them trying to feed on a chameleon. I'll often leave cricket food in the chameleon's cage, too.
I don't know what is going on with your baby. I just don't like his apparent bloated appearance and what seems like excess skin around his throat and eyes. It is possible that he has had some edema that has resolved, leaving stretched, deflated looking skin, however I think he has some edema now. Edema--basically fluid retention--has many causes and sometimes no one really knows why it happens. I have a species that is quite susceptible to developing edema in response to over supplementing, especially artificial Vitamin D. If you have been supplementing him with the Repashy vitamins you showed in a picture, that could very well be what is going on. That's why I recommended you to stop all supplements except plain calcium with no Vitamin D. I've also found that sometimes certain cricket shipments seem to cause edema. I think it is from a build up of something the commercial cricket farms feed their crickets. Other breeders (of the species I work with) have told me that sometimes when they switch from feeding fruit flies and bean beetles to crickets, they get edema that resolves. I always feed my crickets only really good healthy natural food for a few weeks before I feed them to my chameleons, but sometimes that is not enough.
The second picture is a 7-week old baby with the edema I was talking about. This showed up as soon as I started feeding crickets and has since resolved. I include it so you can see what edema looks like and decide if that is what is going on with your baby. Can you see how the throat area is full and bloated all around his whole neck? If you look you can see that there is a bulge of fluid collecting in the tissues between the front legs. Compare that to the two babies in the first picture. Also notice that the eyes of the baby in the second picture are a bit bulgy.
Caring for fragile creatures is challenging and very stressful. It is just not fun, but if you succeed you will have learned a lot about keeping chameleons.
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