This kind of nail problem indicates either poor health or bad eating habits that leads to low level of zinc and iron or there could be a possibility of some kind of nail infection which is causing darkening and cracking of the skin around the nails.
It is important to consult some physician for this problem to rule out any thyroid problems too.. As a home remedy, immerse your nails in lukewarm olive oil for 10 minutes and then massage them for another 10 minutes. Take care of your diet. A diet rich in calcium, proteins,Zine and iron..