My dads dog is about 13 or 14 and still at it. Sometimes he will be fine andsometimes he will act like your dog. We just give him lots of rest and alittles Aspren (The kind people use for heart theropy, it is "enteric coated" not sure if I spelled that right. It is around 80 milagrams)

My dad will also make him get up now and then and work his muscles, it seems to help.

Hope it is no big deal, good luck.