My Bernie became the same way at age 3. It came down to he needed to be allergy tested. I do not mean blood allergy tested your vet can offer. I mean skin allergy tested by a doggy Allergist. Yes they do exist. He was allergic to everything. I mean every thing. We opted to not put him down and proceed with special food and 3 different antigens that I draw a weekly shot from. It it’s not cheap! But he is 11 now in perfect health and he brings to our lives out ways the cost. We could have children so he is our child.