11 year old dane

So I have an 11 year old female dane. She has a sore back end and I give her metacam. She has had blood work done many time. I take her to the clinic often. I'm a crazy great dane mom. Lately she has been pooing in her sleep. It's not everyday, when she does it she does not seem to realize. She still has spunk and sometimes will jump over the couch. My question is has anyone had this problem with there dane. It makes me so sad 😞