I would definitely get the vet out. If after 5 days it's still swollen, it needs to be looked at. I had a horse that ended up with a cut on his leg, and while I thought it was a puncture, being new to horses I asked a trainer at the barn, and she said it wasn't a puncture, was just a cut, to clean it up, and wrap it. Next day, came out, leg was almost 3x the size of her other leg, had MY trainer look at it, who agreed it was a puncture, told me what to do. So after a few days, it still wasn't better so I called the vet out. Good thing I did, because she had two big pockets of infection on the top and bottom of the site, whatever she punctured herself with had hit the bone, and it definitely wasn't going to get better on its own. He had a huge concern that surgery would be required and part of the bone removed because of infection. Fortunately that wasn't necessary and after a few weeks, antibiotics, and LOTS of cleaning, she healed up. Trainers are great but they are human, and they aren't always right. Keep us updated.