Answer #1: It could be due to an
infection, poor nutrition, excessive exposure to detergents or toxins. Nail health is affected by aluminum. stop using deodorants and
antiperspirant -- Anne Burgess Comment
Answer #2: I take a nutritional supplement and my nails recovered quickly from the kind of condition you describe. Read up on nutrition for the right foods can make a difference; my doctor gave me a diet sheet and recommended dairy products and beans and pulses - Ma Wan Comment