This is oftem caused by getting too much Calcium i have had this too and I realized it was because i was getting too much calcium if you are taking a Calcium supplement and eating alot of dairy you may be over doing it just some advice
try soaking your nails in Vitamin E oil. its cheap. and wont cause it to correct itself overnight obviously, but it may help
I read this is nothing to worry about, I have them too. You can google Nail Problems & they will show you pictures of different nail problems. Hope this helps.