She did take him to the vet and they have him on ibuprofen for arthritis
Strange that a doggy NSAID wasn't prescribed. If ibuprofen then a fish oil gel cap once a day will help protect the kidneys. Most likely the dog has some spinal degeneration that is occaisonally pinching a nerve. Periodic Prednisone treatments may help.

In general I've always believed that if the dog has a good quality of life, and most important seems happy and content then it's not time to say goodbye.