Physical therapy advice for my dog... Seriously?

About 3 months ago my beagle hurt his back paw and started limping around on 3 legs. After about 5 days we decided it was time to take him to the vet to see if it was serious. After examining the dogs leg and paw he couldn't find anything wrong so he suggested we give him awhile to see if he starts using it again. Well about a week after that we actually noticed a cut in between his toes on that paw so figured that was the issue. After a while the cut healed but that was about a month and a half ago and he still isn't using that leg. We've taken him on long walks to see if that will help but it doesn't. We also noticed that although he doesn't like to put weight on it that he can with no discernible pain. And finally we just ran out of ideas on how to get him to start using his leg again. Honestly ankle weights are sounding like a good option but not only are they impossible to find for dogs but it just seems wrong so any ideas or advice would be greatly appreciated.