Help! Animal in danger!!

I was walking my dog in the woods today like I always do when my dog saw a fox. I didn't see the fox because it was just lying down in the grass. My dog ran up to it and flipped it over, trying to attack the poor fox. I called his name and after a couple of tries, my dog finally came back to me.

I tied my dog to a tree and slowly approached the fox to check if it was okay and right away I could tell the fox was not. It tried to stand up but swayed and fell over. It was missing fur and the parts where it didn't have fur were caked in mud. The fox wouldn't open his left eye and it was looking at me in fear. I left it alone because I was obviously frightening the poor animal.

I checked my dog for any puncture wounds or blood but I couldn't find any. I'm taking him to the vet tomorrow to get a thorough check and shots if he was bitten by the fox.

The fox's behavior was strange. It didn't run away, I couldn't see it attack back, and it didn't bark to my dog. I'm afraid that the fox is hurt. Who can I call to help the fox? Not animal control because they wouldn't help a wild animal like foxes. I was told DNR but they were unsure if DNR would help a wild fox. I want to make sure that the fox can be helped or if it dies, that it will die peacefully and not slowly. I'm only a teenager, I'm 14 years old and this experience frightened me beyond belief. My dog has never attacked another animal before but he has been attacked a couple of times in his past. Who can I call to help the fox? Please help me.