New fingernail growing under old fingernail?

So my 2 year old was showing his owie on his hand, and upon a closer look, he appears to have a new fingernail growing underneath his old fingernail. The old fingernail is barely hanging onto his finger, and I can clearly see a second nail underneath the original nail, but any sort of contact with the finger causes him great discomfort. It appears as if the same process is going on to a finger on the other hand as well. Any ideas what this could be?

Nicole2014-01-28T20:26:23Z

Omg I had this since I was 10 I'm 14 now. It's vitamin deficiency, I still get it even if I eat vitamins though, once my new nail grew with a hole in it. But I get it less often now.