What's wrong with my dogs leg?

I took my dog to the vet last week because she was limping, I thought she may have broken her leg, $300.00 later it turned out to be a twisted ankle, or so I thought. We've been giving her a medication prescribed by our vet to reduce swelling but now almost a week later she has licked all of the hair off of a spot on her foot revealing a puncture wound of some sort. I can't identify it and I might be looking for a new vet, I'm just looking on here to see if someone else has ever had this issue with a pet and has some insight as to what to do or what it is. She's a collie/doberman mix. 4 years and 9 months old, healthy, 27lbs. and this happened sometime last sunday night while everyone was sleeping.

http://i17.photobucket.com/albums/b75/ellekelly/ca...

here is a link to what it looks like. Thanks in advance!