Corey Feldman was hospitalized Monday after a medical emergency on a flight from Chicago to Los Angeles ended with a rushed trip to LAX and a local hospital. A Los Angeles Fire Department spokesperson said a 54-year-old man was taken in for further evaluation and treatment.

That is the latest turn in a trip that began as a stop for a Stand By Me anniversary celebration in Chicago. On Sunday night, Feldman joined Jerry O’Connell and Wil Wheaton at The Chicago Theatre for Stand By Me: The Film and Its Stars 40 Years Later, then later posted photos and video to Instagram showing the drive to Chicago and a stop in Gary, Indiana.

A source close to Feldman said he started feeling sick on the flight, and a doctor who was also on board checked him out before the plane landed. That detail matters because it points to a problem that was serious enough to draw help in the air, but not so sudden that no one could assess it before landing.

Doctors reportedly believe he may be dealing with pancreatitis or gallstones, though no diagnosis has been confirmed. That leaves the story at the point families know too well: treatment has started, but the reason for it is still not settled.

For now, the clear fact is that Feldman’s journey from a public appearance in Chicago to a hospital bed in Los Angeles ended in emergency care, and the next update that matters is the one that explains what, exactly, made him sick.