Hi Alex,
It sounds like Calcium defeciency desease, but a vet visit is needed to make sure.(it could be other things too.)
There are many forms of C.D.D. The most common is from long term improper conditions. This is understood by vets and is curealbe in the begining stages.
Please consider, CDD is simply lack of placed calcium. Which can have many causes.
Most think of poor care as the case. It can be, but there are other causes that come from what is considered good care.
If a monitor lives in conditions that promote rapid growth, high temps, plenty of choices and is not fed enough to keep up with the growth, then CDD can appear as well.
The longterm form is characterized but thickening of the limbs, softening of the bones, soft jaws are common and twitching. The second type is characterized by twitching, loss of leg(rear) movement and collapsing of the backbone, bumps appear on the backbone.
This second form is cureable as well, but it should be done with vet care. People tend to increase the temps and such, which only speeds up the process.
Both forms are best cured with the administration of Calicum. Please let a vet do it.
I guess the point is, keeping them in good conditions does not avoid CDD. It can expose a different form. Again, the first form, is lack of placed calicum. That is, for whatever reason, the monitor cannot place calicum. It was thought for lack of UV(d-3) But I believe its simply to low of metabolism does not allow for that process.
The second form is not the problem of placing calicum, its simply a shortage of calicum. That is, the need is greater then the supply.
Growth and reproduction express the greatist need for calicum. The keepers job is to support the need. I hope this helps. FR