Since it started recently...
How old is she? Has she experienced winter before? Has it snowed in your area? If so, is it possible she has walked through salt used for melting snow? Have these blisters, then, appeared after such a walk?
Not a vet... just some food for thought. Some salts are deemed safe for dog paws, but even then I've walked a few whose paws are sensitive and burn or get blistered from it.
How old is she? Has she experienced winter before? Has it snowed in your area? If so, is it possible she has walked through salt used for melting snow? Have these blisters, then, appeared after such a walk?
Not a vet... just some food for thought. Some salts are deemed safe for dog paws, but even then I've walked a few whose paws are sensitive and burn or get blistered from it.