You've got lots to think about with some great advice here on the forum. If you'd like to ask a vet for free, use this site. (I've put you on a page for DJD just because it mentions popping, not because I think that is the problem). I've asked Dr. Turner a few questions and he is very helpful. In fact, the site has tons of great articles on health conditions.
https://www.vetary.com/dog/condition/degenerative-joint-disease Have you asked your vet as of yet? I'm not an expert but I tend to think leave your puppy on puppy food until you check with your vet. I hope all goes well!