Hello,
I am going to say that I am pretty sure he is impacted. How old & big is your dragon, can you post a picture so I can take a look at him please?
Also, does his back have a bulge in it as well? Can he use his back legs?
This is probably going to warrant a vet visit.
MBD is metabolic bone disease normally caused by lack of proper UVB lighting & calcium supplementation.
Liver disease is something that does not happen overnight, but is a slow process most of the time. If you feed too many fatty foods especially during their younger & growing years, the liver can take on too much fat & cause problems. They do not metabolize fats very well in excess.
Tracie