I don't know of anything you could give safely OTC, but my 14 year old poodle who weighs approx 10 lbs is on 25mg of Tramadol twice a day for back pain. Tramadol is a non-narcotic and is safe for use in both people and animals (I know because I was put on it after knee surgery!
). Our vet said that she will have to be on it for the rest of her life because an opperation isn't an option
. It's also pretty cheap if your dog needs it for any amount of time. I'm sorry I couldn't help any more, but this has really been a life saver for our dog.