Geez i dont know why Vets go to the same..."it may be a neck or back problem"..and prescribe pain medications that just puts them zoned out.
Any chance your dog moves slowly or shake at all? There is a condition called "Beagle Pain Syndrome".. thing is its Meningitis. My vet never heard of it. PLEASE DESCRIBE YOUR DOGS MOVEMENTS...
If that is the case then the pain medications do nothing.. get the dog on a round of Prednisone and off the pain meds.
Google...Beagle Pain Syndrome
My dog was better after the first few Prednisone doses and hasnt had a problem since.
My vet wanted to do an MRI for $2,000..that wouldnt treat the condition except you have a big bill.