sharp pain in my belly button

This morning as I was walking into work, I felt a sharp pain in my belly button. It lasted about 30 min. Does anyone know what this means? Keep in mind I'm 37 weeks 4 days pregnant. The baby is moving less, but he is moving. It wasn't unbearable pain, just weird. Has anyone else experienced this? I'm having doctor appointments every week now so I'll definitely inquire about it tomorrow.