Charlie Sheen suffered a hiatal hernia in his stomach -- not an overdose -- and it may have triggered the 911 call that landed Charlie in the hospital.
Sources tell us the hernia is located in Charlie's stomach. The condition causes acid and food to back up into the esophagus ... and we're told it causes "horrible, horrendous pain."
Charlie will spend the night at the hospital.
We're told Charlie has had a hiatal hernia for years.
As we previously reported, Sheen was hospitalized early this morning.