I have a six week old bottle calf that has lost all the hair around his tail end and down the inside of one legs as well as the upper end of his tail. I have never seen this before. I am not sure what is causing it. He doesn't seem to scratch. There are no irritation or raised areas. No crusty surfaces or scabby areas as you would expect with ring worm or lice. Just bare skin. It doesn't seem to be spreading. On his tail, the hair seems to be sluffing off with part of the skin attached -like it's shedding. The skin underneath seems to be perfectly fine - not red, sore or raw. He was on antibiotics for a while - naxcel but that was weeks ago. He eats grain and hay, but not as much grain as I would like. He doesn't seem to care for calf manna, but I mix it with his grain anyway. There's another calf that has been his stall mate all along and he doesn't have any hair loss. Any ideas?