Actually, I saw your other photos too and I don't know any more. I'm comparing it to other veiled elbows and I guess he looks more normal? lol Not sure, sorry, I'm just used to seeing elbows with more pointiness.
If he does have MBD, it would be very mild. Nothing too serious that can't be stopped right now. All you'd have to do would be to continue with your schedule so far, because it sounds good. What is nutrobal though? If they're vitamins then twice a month lightly is fine, as well as D3 lightly twice a month. Some people prefer to give D3 and vitamins just once a month, but I think if you do it lightly, it's probably easier on their bodies to take it in in two times instead of all at once.