How often is he getting an antibiotic injection? Do you know what the medication is called? I just want to make sure that you know an antibiotic is more than a one-time thing. Usually, it consists of a series of injections at regular intervals.
I also agree with what
@skywes13 has advised.
To go a little more in-depth on supplementation, D3 is an absolute must. Jacksons chameleons are sensitive to over-supplementation, but this just means that we have to be a little more careful. When looking for a calcium with D3 product, you want to look for something with low D3. An excellent choice is Repashy Calcium Plus LoD. The "LoD" specifies that the supplement has lower D3 levels than Repashy Calcium Plus. Make sure to get the one with LoD! Repashy calcium plus LoD should be given twice a month. This supplement also has a multivitamin, so need to get a separate multivitamin supplement.
Link for LoD:
https://www.amazon.com/Repashy-Calcium-Plus-LoD-JAR/dp/B00DLJRMV2
In addition to the D3 and multivitamin given twice a month, you need a plain calcium supplement that you can use on every feeding to balance the phosphorous to calcium ratio of some feeders. Feeders that need to be dusted every time are crickets, dubia roaches, and superworms. You don't need to dust insects such as black soldier fly larvae, silkworms, and hornworms. Some good plain calcium supplements are Arcadia Earthpro-Ca and Repashy Supercal NoD.
Earthpro-Ca:
http://www.lightyourreptiles.com/arcadia-earthpro-ca-calcium-100g/
or Supercal NoD:
https://www.amazon.com/gp/product/B00N3BKCGA/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1
And for gutloading/feeding your feeder insects: the goal here is to feed what is nutritious for the insect. This way the insect is as healthy as possible for your chameleon to eat. You can get commercial gut loads such as Repashy Bug Burger. Or you can use the fresh veggies and grains mentioned in the gutloading sheet posted above by skywes. Do not gutload with a calcium food.
Concerns: Do you ever see your cham basking on the single branch provided? It seems almost out of reach. Additionally, you need to add a lot more branches. He is too big to be walking around on a small shleffera.
I find it hard to believe that your cham is getting the proper temps and uvb needed to thrive. UVB and heat need to be absolutely perfect. If the basking temperature is too low, he will have a hard time digesting foods, as well as synthesizing vitamin D.
Additionally, if you are using this version of Fluker's Calcium Cricket diet, then it has D3 in it:
https://www.chewy.com/flukers-high-calcium-cricket-diet/dp/126140?utm_source=google-product&utm_medium=cpc&utm_campaign=f&utm_content=Fluker's&utm_term=&gclid=Cj0KCQjw0oCDBhCPARIsAII3C_Hy0AcuWreW7dPMBIfk64fZ9BCcRY2Muo094g7C4_u_ouglYskaVOoaAvbBEALw_wcB
I'm not sure of the D3 levels, but if you are only feeding crickets, then over-supplementation of D3 could be possible.
@kinyonga might know.
Perhaps the D3 is redistributing the calcium from the bones to other parts of the body--hence the bumps under the skin?
You really need to get a temperature probe to check out the basking temps. Like
@skywes13 said, you need a t5 HO uvb bulb. Likely, you are over supplementing and under exposing your cham to uvb and heat. You need to add more branches and more plants.
