You need to nourish your nails. I recommend a nail strengthener.

It is a product called Kerasel Nail. It helps people with athlete's foot, those with weak fingernails or toenails that crack or break, and it turns black nails white. I noticed the effects quickly if I used it consistently. As long as you apply the right amount and let it absorb well, your nails will improve fast. It is the best nail nourishing product available.