nails splitting

My 5yr old daughters nails are splitting. During school last year she got 5th disease, then over the summer she got a bacterial infection which caused her to have strawberry tongue, and red dots all on her hands and feet, and it was treated with antibiotics. I'm not sure if its related to this at all but it seems like it started about a months after the infection. the first one was on her hands and one split real bad, her teacher had a band-aid on it so it doesn't rip off and bleed and I finally got it off, and now her big toe is doing it now and bleeding. Its splitting crosswise from the way its growing and happens on all her nails, a little. So what is this??? Why is she getting this?