you can over supplement as well which is not good. MBD, or Rickets is a very bad thing, but it can be stabilized with the proper nutrition, but his knots could remain such as bad arthritis does to humans. Convince you buddy to take him to the vet, and he will be able to if need be supplement him. And also ask to see if he seems to have stabilized, or if its going to continue to get worse, and make his life nothing but painful. what is the recommended vet check for x-rays to see how the bone structure is