He does have MBD.
The way to correct it is to have a vet give him injections of calcium and liquid calcium sandoz or gluconate until his blood calcium levels are back to normal and his bones are strong again.
You also need to make sure that your chameleon has exposure to a UVB light, appropriate basking temperatures, properly fed/gutloaded insects and supplements to keep it from returning.
The most often recommended UVB light is the reptisun 5.0 long linear tube light. It should be replaced every six or so months.
Basking temperatures should be in the mid to high 80'sF. You can use a regular household incandescent light bulb for this.
Since many of the feeder insects have a poor ratio of calcium to phosphorous we recommend dusting the insects just before feeding them to the chameleon with a phosphorous - free calcium powder to help make up for it at most feedings.
It's recommended that you dust twice a month with a phosphorous - free calcium/D3 powder to ensure that the chameleon gets some D3 without overdosing it and leaving the chameleon to produce the rest of the D3 from its exposure to the UVB light. UVB from supplements can build up in the system and lead to overdoses but D3 from exposure to UVB won't likely build up as long as the chameleon can move in and out of the UVB when it wants to.
It's also recommended that you dust twice a month with a vitamin powder that contains a beta carotene (prOformed) source of vitamin A. PrOformed sources of vitamin A cannot build up in the system and lead to overdoses like prEformed sources can and this leaves it up to you to decide whether the chameleon needs prEformed or not.
Hope he will recover quickly!
