splitting nails

My fingernails are splitting and it is driving me crazy. My sister told me that when she went through the hairloss phase of her alopecia universalis, her nails looked like someone took a hammer to them. Mine are vastly different. They have become brittle and have vertical ridging. Supposedly the biotin that I've been taking is helping, but somehow I doubt it. It is very painful because the nail hardener isn't helping anymore.