Based on the symptoms you have described, there does not appear to be an immediate emergency. I presume that the glass piece entered the sole of the foot. It is important that tetanus vaccine had been given as per your pediatricians protocol earlier .I also presume that there is no fever or local redness at the site etc. It is very unusual for a glass piece to produce numbness in this manner hence a visit to the doctor is essential. It is also important to make sure that there are no remnants of any foreign body such as glass/sand in the wound. You may apply an antibiotic cream such as soframycin as well. To put it briefly: Take a copy of your child s current tetanus vaccination status, visit to a doctor to rule out causes of numbness such as nerve related problems which is highly unlikely here, Also to ensure that there are no tiny pieces of glass and or other foreign bodies in the wound,Application of antibiotic cream . Stepping on a piece of glass is a frightening experience for a child so do ensure that you address her anxieties and make her less anxious.Trip to doctor and confirmation that things are ok will help both child and parent as well.Should you require further assistance please feel free to address your queries here and I am happy to provide you with further information .Warmest regards