The pads on my dog's feet fell off. What can I do to help?

My German Shepherd went on a run on the pavement, and I noticed two of the pads on her feet fell off, and it looked like he had calluses. He has a nuerological condition that makes his kind of drag his back legs, so he wears booties on his feet. His feet have been really bothering him because of the pads, and he can barely walk. What is something I could put on them to help them heal or relieve the pain?