She may have a splinter in there. I'd do some soaks in Epson salt water 1 cup to 1 gal of warm water let her stand in the bucket both feet since its easier and just hold on to her try to keep her in at least 5-10 mins each time. After she has soaked use some noesporin or triple antibiotic on the area, and when you can get some colorless iodine[walmart carries it] or CVS after a good soak and dry use the iodine paint top and bottom then let it alone for a few days, then check and let us know what it looks like. Hopefully the ES will help draw out any thing that maybe in there and the iodine will clear up any infection. Keeping her confined like you are will help keep it cleaner. FYI don't let her drink the ES water it is also used as a laxative.