My Eighteen Month Old Granddaughter Was Playing "horsie"and Her Wrist

My eighteen month old granddaughter was playing "horsie"and her wrist popped as she dropped to the ground. A distance of about 1 and 1/2 feet. Mom was holding on to her wrist as the baby slid to the ground and felt/heard the pop. It happened about 20 minutes ago. There is no swelling, but the baby is still crying, whimpering, and not wanting to hold anything with that hand. She keeps reaching for the wrist with her other hand. Does she need to see a doctor immediately, or wait and see?