How can i treat my dogs pressure sore?

Last summer, a pressure sore appeared on my dogs shoulder. He has a thing for sleeping on the bathroom floor. We try to get him on the carpeting or put a towel under him but he likes the coolness of the tiles. The problem was that he keeps licking at it and putting more pressure until one day it got so bad that we took him to the vet. The veterinarian gave us a cream to apply and told us to keep it cushioned at all times. She covered his shoulder with pads. The problem is that since it is at the very top of his arm and right on the bend, it slides down. We've tried shoulder pads, socks with a rubber band, ace wrap, and so much more but with in a matter of minutes it slides down. We don't want to cover him with something that will keep him from being able to bend his arm. Especially because hes always going up and down the steps and we don't want something to happen. Last year we went to the last resort by taping on the pad with the cream but of course it wasn't good when we had to take it back off. We really need to find something to use before it gets infected again or worse. Any suggestions please? Were thinking of shaving around the area so that we can apply tape again but we would rather not. We just need to find away to be able to keep the pad with the treatment on and some sort of cushioning that won't slide down. Thanks for your help!