I haven't read all you post because my phone won't load it for some reason but from the first half it's very much more than likely it is because of the skin is loose and he can't breath properly. Wait until he sheds every last piece and it will go away. Only then if it doesn't you'll want to consider an ri
the popping would also more thsn likely be shed related. As he breathes out the skin might be moving away from the new skin and making the popping noise