4m old st Bernard has problems with hind legs vet says its nerves how can that be treated I don't trust the doc and theres no one else for the time being has anyone had a similar experience?

Damaged nerves is a serious thing to happen to a dog. A lot of dogs have had nerve damage and have made progress to regaining mobility. The pup is young so that is in its favor.

The vet knows things that should be listened to, trust in what he sais and let time show the results.