Well, I can't tell anything from that photo.
Post injury...day 3 will be the day of greatest inflammation and pain. After that, on days 4 and 5, inflammation should quickly decrease and then continue to decrease over several days/weeks depending on the extent of the injury. If it doesn't decrease and instead continues to worsen on days 4/5, then you've got a serious problem which would require veterinary attention.
However, since you've now given her bute, there's no way to monitor this injury because you've artificially taken away the inflammation and pain.
I suspect it's nothing of great concern and in a week to 10 days she'll be fine, but without proper pictures/video, we have no way of knowing for sure.
Sooooooooooo, if you are concerned, you should call the vet. And no, if you have to ask what appropriate treatment would be for this situation, then you shouldn't be applying any. Talk to your vet.