What Causes Yellow Discoloration On Nails?

Hello doctors,

About 10 months ago I painted my toes for a wedding I went to and I didn't remove the nail polish (I know I'm very lazy) my toenails just grew and eventually the polish had been cut off on all my toes except my two big toes... Before I knew it my two big toes had turned yellowish and they weren't growing anymore... Then they kind of detached from the nail bed and I've been growing new nails underneath both of them. The one on my left foot fell off today and the nail that was underneath is oval and totally fused to my skin with no overhang at all. I fear the one on my right foot is going to do the same... I wanted to know if this is normal because I have read about people damaging their toes (eg. Dropping something on it) and their mails fell off but I'm just worried because it's both of my big toes and I haven't damaged them at all...

Thanks in advance for your help.