Dog might have to be put down advice please?

I have a 6 year old Miniature Schnauzer and for awhile now he's become weaker. The vets can't quite put their finger on it. When he gets real bad he can't walk or even stand up. He had medicine for awhile and it help a lot. But recently it hasn't been helping him. He has some good days and some bad days. Any Idea of what it could be or things we could try before having to put him down? My mom wants to out him down because she doesn't know what else to do. But I don't he's my puppy I've known him since he was born and I don't want to give up on him. We already made it through the struggle of when we found out he had brain damage from when he was born so he has special needs. And I want to try more before we put him down. His symptoms are unable to walk or stand (some days), weight loss, sleeping a lot, some depression, whining when picking him up. Any advice would be appreciated

The inability to walk or stand suggests a neurological problem - like a herniated disc in the spinal cord or neck area or a tumor on the spine. Unexplained weight loss is most often - cancer. You either need to find better diagnostic vets or you can try seeing a holistic vet which uses acupuncture. They can sort of read the dog (& what's going on, thru the acupuncture points that are "off"). Some points can be treated to help and inflammation & pain can be decreased. The vet may not be able to cure the dog but may offer a different diagnostic window into what is going on, w/o expensive tests. If your dog is terminal, keeping the dog comfortable is important.I've started using a holistic vet & have a number of dogs helped by acupuncture for various issues.