You need to get the nutrients back in balance and then keep them there.
You said you used Reptocal ...it has prEformed vitamin A in it. Do you dust with it every time you feed the chameleon?
When balancing the nutrients you need to look at the supplements, what you feed to the chameleon, what you feed to the insects...and the UVB and appropriate temperatures too.
Here's what I do to maintain a balance of nutrients and why I do it....
I use a long linear fluorescent Repti-sun UVB tube light on the cages in a double fluorescent fixture. The other bulb in the fixture is a regular household fluorescent tube. If its a male veiled I also use a regular incandescent household bulb of a wattage that will put the basking area in the mid to high 80's. I use the Repti-sun tube because it is one that has had no bad reports against it. There should be no glass or plastic between the chameleon and the UVB light. The exposure to the UVB allows the chameleon to produce vitamin D3 which allows him to use the calcium in his system. Appropriate cage temperatures also play a part indirectly...heat is needed for proper digestion and thus nutrient absorption.
I dust the insects before feeding them to the chameleon at most feedings with a phosphorus-free calcium powder to help make up for the usually poor ratio of calcium to phosphorus found in many of the feeder insects. (I use Rep-cal).
I dust twice a month with a phos.-free calcium/D3 powder (Rep-cal with D3) to ensure that the chameleon gets some D3 without overdoing it. D3 from supplements can build up in the system so I leave the chameleon to produce the rest of the D3 it needs from its exposure to the UVB light. The UVB from the light shouldn't cause any overdose as long as the chameleon can move in and out of the UVB.
I dust twice a month with a vitamin powder that has a beta carotene (prOformed) source of vitamin A since beta carotene won't build up in the system. There is controversy though about whether chameleons can convert the beta carotene...so some people give a little prEformed vitamin A once in a while....but it leaves the control in the owner's hands this way. Excess prEformed vitamin A may prevent the D3 from doing its job and lead to MBD.
I also gutload/feed my insects a nutritious diet. I give crickets, locusts, roaches, superworms a wide variety of greens (dandelions, kale, collards, endive, escarole, etc.) and veggies (carrots, sweet potato, sweet red pepper, squash, zucchini, etc.).
As for the
hypervitaminosis...if your chameleon has been getting too much of the vitamins that build up in the system...I suppose all you can do is not use them for a while. Did the vet not say what to do??
Here are some sites with good information that might help....
http://chameleonnews.com/07FebWheelock.html
http://web.archive.org/web/200605020...Vitamin.A.html
http://web.archive.org/web/200406080...d.Calcium.html
http://www.uvguide.co.uk/