A vet can tell you for sure if its a calcium imbalance and could give your chameleon injections of calcium to raise the blood calcium levels. When the blood calcium level is high enough the chameleon can be given a shot of calcitonin which will draw the calcium back into the bones. This is the fastest way to recovery.
Assuming that it is MBD, once you bring your chameleon's calcium levels back into balance you need to keep them there. Calcium, phos., D3 and vitamin A are the main players in bone health and need to be in balance. When trying to attain the balance, look at your supplements, what you feed the chameleon and what you feed to the insects that you feed the chameleon.
I don't know what supplements you got...but..
most feeder insects have a poor ratio of calcium to phosphorous, so dusting at most feedings with a phos.-free calcium powder will help to make up for this.
Exposure to UVB (either sunlight or a UVB tube light) will allow the chameleon to produce vitamin D3 which will allow the chameleon to use the calcium in its system.
Dusting twice a month with a vitamin powder with a beta carotene source of vitamin A will ensure that the chameleon gets its vitamins. Beta carotene sources of vitamin A will not build up in the chameleon's system however there is controversy as to whether all/any chameleons can convert beta carotene...so some people give a little preformed once in a while. Preformed vitamin A builds up in the system and can prevent the D3 from doing its job and lead to MBD....so don't overdo it.
If the chameleon is only getting UVB from tube lights you may also have to dust with a phos.-free calcium/D3 powder twice a month. D3 from supplements can build up in the system so don't overdo it either.
Appropriate basking temperature helps with proper digestion, thus plays a part too.
Hope you can get your chameleon back on track!