Try your best to find the reason of eating her finger. If she suddenly develop this bad habit, very possibly that is because of some pressure. Does she have some trouble that makes her feel upset, nervous? For example, scare of some big kids at day care? Have trouble of getting along with other children? Scare of a teacher at day care? Is there any pressure at home? Talk to her just like a friend of her. To see if she can tell you some secret that happened in daycare, or somewhere, that makes her nervous. For me, I finally find the reason and did whatever I can do the help her. Now, my daughter’s nail has grown up again, but I am still not for sure if the bad habit has gone. Hope this can help