Hello Dot. I'm sorry your dog is not well. He is a good age, and depending on the breed, he is really quite an old dog. Many dogs get lumps under their skin as they age, which are usually benign fatty cysts, which don't cause any trouble or discomfort for the dog unless they grow too large, which is why the vet said to keep an eye on any changes in them. Regarding the back legs, with old dogs, and especially with some breeds particularly larger dogs, the back legs gradually become weaker. This is particularly noticeable when they try to get up after sleeping, and when getting up steps. Unfortunately, one day the back legs become so weak that the dog is not able to rise to a standing position, and this can happen quite suddenly. Sadly, then it is decision day, as there is nothing further that can be done. As long as a dog is managing, and seems happy in other ways, vets sometimes recommend a wait and see time, to give the owner a bit longer with their beloved pet. This is what happened with my Jock (labrador/alsatian cross) several years ago, and more recently with my next door neighbours border collie. I do feel for you, as it's so sad when our dogs not well. I hope your vet can explain things for you, and hopefully let you and your dog have more time together. Sorry I can't give you better news, but I shall be thinking of you on Friday. Good luck. Schutz.