Mastiffs

I have an english mastiff that is limping around and not wanting to put any pressure on one of his back legs. I know that he injured it last week when we were playing around with him in the back yard. He was limping for a few days, but then it seemed to be getting better, he was starting to be able to walk almost normal again, but when I came home last night it was like it was worse then before. I can touch him and he is not seeming like he is in pain when I feel around on his leg, but It is concerning me. I know that if I take him to the vet they are going to tell me to wait it out, just like they did the last time we took him in for the same kind of situation. Does anyone have any suggestions for anything I can due in the meantime?