S.H.
Withholding water is the worst thing that can be done for the kidneys and obviously it's not working anyway.
If I understand correctly this is a new thing? Only for a few months and before he was dry? Has he had a vaccination or dental work done? Mercury can cause bedwetting and there's mercury in most vaccines and also in amalgam dental fillings which are still legal and dentists are not allowed to tell you they're not safe.
If that's the case I can send you some info on how to get rid of it. My daughter was a bedwetter until we got rid of the mercury overload in her body.