The dooger could also have kidney or urinary problems as well.
Way too soon to talk about putting the dog down at this point....
Needs a doctor first. Please take him to the vet for a second opinion and give us an update.
This is abnormal behaviour.
Don't know what tests your vet has done?
But this dog needs a few tests.
If your vet said your pet is fine and did not do any testing, then imo it's time to change vets.