You need to determine if it is actually swollen or if the fur is just missing. I can't really tell which from the photo. Also if there is any crustiness around the nail or on the skin. Again, I can't tell from the photo. If you want to post another photo, it needs to be a clear close up of the problem, where you can easily see what the problem is in the photo. Then we might be able to give you an idea if there is a problem with the toe or not.