Tell me about losing a nail? How does it feel? How long until it grows back? When does the pain stop?

My 2.5 year old got her thumb smashed in an interior door this weekend. The doc told us she would lose her nail. It's already gone. I'm not sure where it went or when. She's wearing a splint to protect it from bumps but it's not staying on well. It seems sensitive to everything. She's reluctant to use her hand and cries when we clean it or change her bandage. The original injury was Sunday, it's now Tuesday. Please tell me it gets better.