Has anyone else had this nail problem?

I normally paint my nails often but I haven't for a couple months due to them looking pretty yellow and dry. Tonight I was trying to figure out why the whites on my toenail went all the way down to my cuticles on one corner and I realized that my toenail is falling off. I'm not sure why though. I haven't injured it and I haven't had any signs of a fungus either. My boyfriend thinks it might be a lack of vitimans and I should cut the nail off. I don't want to have a  toe with no nail though! Even if I wear closed toe shoes it'll still probably feel weird. Has this happened to anyone else? If so can you help me figure out why this is happening, and what should I do?