My beagle won't walk on his hind leg... Please help.?

Hopefully, the pain meds. were something you already had from a vet??? I doubt this little guy is going to let you ice the sore area. If possible, crate him tonight, so he can't move around on the leg. (Also, keep his area quiet). Please, get him to a vet's office ASAP in the morning. Praying it's nothing too serious.