You have not mentioned whether it was permanent or baby tooth. If it is a baby tooth then nothing to worry as it is about to shed at this age and has to be replaced by adult tooth. if it baby tooth has already shed and it is an adult tooth then you have to save this tooth as a 7 year old child, root completion is not there and so conservative treatment is done so that vitality of tooth can be saved and root completion is there. Visit a dentist who will take xray and do clincal examination and do the needful. for more info on children teeth emergencies http://www.identalhub.com/dental-different-types-of-children-dental-emergencies-793.aspx