Angus,
George is our 10-1/2 yr old English Mastiff. Normal life for this breed is around 7 yrs, so he's a really old man. Currently weights in at 225 lb.
He started draging his rear about 4 months back and could not get up on his own. I started him on Cosequin DS Plus MSM and noticed a differance within a week. After two weeks he was getting up on his own. Expensive but Costco online is much cheaper then the big pet stores.
For pain, he is on 400mg a day of Novox, a generic form of Rimadyl, simular to Petprofen. My Vet wanted over $6 for a day's dose, but I found it at an online pharmacy for $2 a day.
He's doing a heck of a lot better then before, so if there is hope for an old man like him who is way past his expected time, there is hope for your puppy. Don't give up hope, until you give remedies time to work. Even the anti-imfammatories can take 1 to 2 weeks before an improvement is seen.