Based on what you've posted, I strongly believe your cham's tongue problems are being caused by his supplements.
I also doubt that there would be any benefit to your cham whatsoever by reducing his calcium intake at all.
Believe it or not, elevated blood calcium levels can be caused by excessive D3 intake.
Any dietary excess of calcium is readily eliminated from the body--unless there is also too much D3 intake.
Please read all that I have written before discarding my hypothesis.
Specifically, he is getting supplemented with
too much D3 and no other vitamins.
Miner-All-I is described as a Calcium / Mineral Supplement - Phosphorus Free Calcium with Vitamin D-3
(Calcium is a mineral and trace elements are also not vitamins)
Excessive D3 does some
very bad things when chronically overdosed.
Internal organs (heart, lungs, kidneys, etc), soft tissues and blood vessels can become calcified causing the organs to not function well, if at all.
The tongue dysfunction can be an early warning sign of the excessive D3 or the result of a vitamin deficiency.
Miner-All-O is a Calcium/mineral supplement containing zero vitamins, Miner-All-I which is identical, except it contains 1 vitamin, vitamin D3---meaning it lacks all of the other 12 known essential vitamins.
This leaves him lacking in all 7 vitamins in the B vitamin complex group as well as vitamin A, vitamin C, vitamin E and vitamin K.
It is possible, that he
could be getting enough of these vitamins from your gutloading , if it is
outstanding but it is more likely that he is lacking in some or all of them, as very few gutloads are that carefully constructed by the average chamkeeper.
Most vets are not treating nearly as many creatures who receive D3 supplements as they do ones who do not get vitamin supplements at all.
Given the large number of exotics on the market today, it can be very difficult to keep up with the exact nutritional requirements for each species and that is if the exact requirements are even known.
For many exotics, chameleons included, there have not been enough studies to determine the precise nutritional needs, so we rely upon the advice of those who have been long-term successful cham keepers.
Their advice:
Feed the feeders a
very nutritious diet and supplement as follows, to avoid deficiencies
calcium without D3 at most feedings
calcium with D3 2x a month
Multivitamin 2x a month
(ONLY USE HALF THIS for Senegals, Jackson's and other montane types of chams.)
If you're using the Indoor Miner-all and Rep cal with D3--then he is getting a
huge amount of D3.
RepCal with D3 contains a relatively
HUGE amount of D3 when compared to the other popular brands of calcium with D3.
For example
RepCal with d3 has 400,000 IU/kg of D3 (This is 20x to nearly 100x the other calciums with D3)
Repashy SuperCal LoD has 20,000 IU/KG
Zoo Med's ReptiCalcium has 22,000 IU/kg
Exoterra Calcium +D3 has 32,000 IU/kg
Sticky Tongue Farms: Miner-All-I 4,400 IU/kg of D3
Figures taken from here
https://www.chameleonforums.com/blogs/sandrachameleon/174-whats-supplements-brand.html
If he was mine, I would completely eliminate the Rep Cal with D3 from his supplements and see if he dramatically improves over the next month or two.
I would also change the Miner-All-I to 1x a week and instead use the plain RepCal without D3 for most dustings.
This would effectively give him total monthly D3 much more like the other calciums with D3 and the added micronutrients that Miner-All has in it..
You still need to add a multivitamin, such as Reptivite 2x a month.
Then you will be giving your cham supplements that are much closer to the recommended calcium without D3 at most feedings
calcium with D3 2x a month
Multivitamin 2x a month
If anyone disagrees with what I've written, then feel free to add to this discussion but do so with facts and mutual respect, which go a long way in any discussion.
I'll end with a quote from Sandrachameleon's Tongue Troubles blog
https://www.chameleonforums.com/blogs/sandrachameleon/232-tongue-troubles.html
If your chameleon began missing its prey or not shooting its tongue like it used to, getting worse gradually over time, check your gutloading and supplementation. Poor tongue control / Missing the insects can be a sign of a Calcium, magnesium, zinc, or B vitamins (B1 in particular) deficiency, and /or sometimes maybe vitamin A deficiency (usually not the sole reason), or Vitamin K deficiency, or an inbalance between Calcium, magenesium, vitamin D, and vitamin A, etc. A good supplement or improved gutload containing these nutrients in the correct balance usually helps within a week or two if vitamin deficiency is the reason, and the case is not too far gone.
Over supplementing can also be the source of issues. So if you are already provide a fair bit, consider a temporary respite.