This is not real unusual for a mini. It seems that all of that inbreeding that has been done to get them smaller and smaller has created some real problem like deformed faces, mouths and legs.
When they are as severe as yours is and are already older (than a newborn), it is very difficult too do anything positive with it. The joints are now also deformed and the tendons and ligaments have be even more damaged than they were at birth. You can try splinting, and by all means, get the feet shortened. Most of these little guys just get put down because there is no good solution and any real solution would cost several thousand dollars and would still not be guaranteed to work. If you had the money and wanted to spend $10,000.00 on this poor little guy, the outcome would probably be the same.
I am so sorry that I cannot offer a better solution.