Hi there!
If your dog is not having any other problems, like not-eating or runny stool or lethargic, than it might simply be dog warts.
They can be picked up from a dog park or when socializing with other dogs. If it is this, it is not contagious to people but is to other k-9s. It may spread to other paws or to your dog's mouth, but it will clear up on its own. My dog had this and it lasted about two weeks.
If your dog is not doing well and is having other symptoms (like those I mentioned above) than I would suggest taking him or her to the vet for a proper diagnosis ASAP.
Good luck :-) And do let me know how it turns out.
It sounds like a grass seed awful thing with barbs that work there way into paws and ears.Keep the fur on his feet short and check all the time for these damn speargrass seeds also check near the inside of his ears and keep fur near his ears short.
You can try putting a compress on it to hopefully come out the other side but I think its a job for your Vet as it can get really painful.Stay away from areas where this awful speargrass grows.
Look in between his claws and there should be a raised red lump.
If not..... well Im stumped.lol.