How To Treat Pale Yellow Growth Of Nails?

hi, over the pass 2 months (about), my finger nails are looking quite strange. like regular nails that grow they look lighter than, the ones on the finger. since it grows over. like perfect french manicures. but mine are different. its like the lighter part is going further down, its not exactly white but a lighter yellow. but not to deep. it seems to be happening on all of my nails. and im afraid it might fall off. do u know what's causing this?