Nothing other than try wrapping the paw in something cold for 10 min at a time to keep swelling down and numb the foot for a breif time. Do not leave the cold item on the foot for more than 10 minutes. Wait at least 10 minutes before doing it again. Also wouldn't hurt to 'fast' your dog tonite: water only, no food... this will help in case the doctor wants to use any anesthesia on your dog. Blessings to you and your furbaby - Blu
Sorry I can't help with an emergency pain relief, I have never used anything like aspirin but I suppose there are some "human" pain aids that can be used. DId you check the web with a search on your issue?
Have you checked the paw for any visible cuts or worse something sticking out of the paw, look on the sides too.
You may have already been to the vet, the best answer. Let us know what you learn and how your dog is doing....good lluck.