maybe , just maybe, you could be lucky and it could just be mud rubbing between her toes, or a bit of twig. So a quick inspection, without upending her, get the mud out with your fingers and a squirt with some fotrot spray or terramycin spray would be my first move....then see how she goes. this may hold things at bay untill after lambing when you can do a proper trim without worrying about the babes.
LOL, yet another opinion!
Emma T