had the same injury on my dog 3 yrs ago, but it was a back toe, the vet said it was a deep nail infectionand gave me some antibiotics 6week later he was still saying it was an infection, so i went to a different vet and before i lifted the dog onto the table he said the toe was broke and needed to come off, 3 weeks after the operation she was running around as good as new,and the operation cost a lot less than 6 weeks worth of antibiotics, so in my experience its best to get a 2nd opinion, hope you get it sorted mate