She could have scald and a deep rooted infection. Why not try herbal remedies? According to my herbal book she says..... Purge the animal then build up with good foods such as oats, wheat, given crushed and mixed with mollaases and pulped carrots. This last food is a very valuable tonic for sheep. Be careful not to feed too much oats or wheat though. Give plenty of kale, rich in healing sulphur. For external dressing of the feet eh out all the dirt from the clefts, cutting away sufficient horn to allow the inner sensetive parts of the foot to be reached. For dressing use pinewood tar or stoclkholm tar mixed with powdered barley and mollasses, which should be rubbed well into the feet and lower area of the legs. Or equal parts of Stockholm tar and castor oil make a good salve. To effect a speedy cure the sheep should be folded on to clean dry straw, straw covered yard. Afterwards they must be pastured on dry ground. An effective treatment used by welsh farmers is tar and salt. Two or four ounces of salt to every half pound of tar. It must be remembered that the natural home of sheep is on stony hillsides, where vegetation is sparse. The. The exercise over hard ground and the leaness of body due to low diet, all keep the feet firm and in good condition. Damp, lowland pastures and rich feeding cause foot rot.
I hope this helps, just a little info and I hope she gets better soon. The word of warning about the grains was from me because sheep can get bloated easily, I hope she gets better. Also when feeding them carrots remove all stringy bits from the carrot, as these can cause the animal to choke.