Conversation so far:
Who were Dion and the Belmonts?
Dion and the Belmonts were a leading American vocal group of the late 1950s.
Who were Dion and the Belmonts' members?
The established trio of Angelo D'Aleo, Carlo Mastrangelo, and Fred Milano, formed a quartet with Dion DiMucci.
What happened in 1957 to Dion and the Belmonts?
After unsuccessful singles on Mohawk Records in 1957 and then on Jubilee Records, Dion DiMucci was paired with The Belmonts.
Did Dion and the Belmonts collaborate with anyone?
This early success brought them their first major tour in late 1958, with the Coasters, Buddy Holly and Bobby Darin
Did Dion and the Belmonts tour?
Dion and the Belmonts were on the Winter Dance Party tour with Buddy Holly, Ritchie Valens, and The Big Bopper J. P. Richardson but avoided the plane crash.
Did anything happen in 1960 to Dion DiMucci?
In early 1960, Dion DiMucci checked into a hospital.

Question: Why did he check into the hospital?
Self-contained rewrite: Why did Dion DiMucci check into the hospital in 1960?