My son had this happen 15 years ago at the age of 6-7. He had a cold on Wednesday, and Friday night we were in the ER. His oxygen level was so low he had to be put on Oxygen and admitted immediately with a severe case of pneumonia. No one believed me when I told them his cold started on Wed. He spent 9 days in the hospital some of it spent head down so the Respiratory Therapist could pound on his back to move all that junk out of his lungs. he had 3 oxygen treatments every day. It scared the living daylights out of me. He was a champ. I slept by his bedside every night. I though I might lose him.