My 4 year old son wakes early every morning for the last five days complaining of a stomach ache and then throwing up what appears to be a clear mucus. We run a cool mist vaporizer during the night and limit his food and drink intake during the evenings to a more bland diet, and we prop him up on a pillow to sleep to keep his upper body a little more elevated - but all to no avail. He s fine throughout the remainder of the day. He went through the same ordeal last year and was seen by both the emergency room who simply prescribed a medicine to merely cease the vomiting, following by a visit to his pediatrician who guessed that it could be just post nasal drip. However, this year he doesn t seem to have any congestion which could be the cause. When he was two years old, he suffered from CO poisoning with complications arising after his recovery - stomach aches and vomiting frequently throughout the day and night. He was finally put on Prevacid, a proton-pump inhibitor, for the duration of six months which stopped the episodes. The physician had concluded that the CO poisoning had likely caused damage to his organs, leading to acid reflux. Yet with this previous experience, his current pediatrician is uncertain and doesn t give us any recommendations. I would appreciate some insight.