Ray J Hospitalized After Billboard Awards

Ray J crashed and burned the morning after the Billboard Music Awards ... and landed in the hospital ... TMZ has learned.

We're told Ray J was extremely upset after his confrontation with Whitney Houston's family -- notably Pat Houston -- during the awards ceremony. On Monday morning, someone went into Ray J's hotel room and realized the singer was "out of it" and couldn't get out of bed.

We're told Ray J was extremely disoriented and was immediately taken to the hospital by ambulance.

As for what happened ... it's looking like a combo of exhaustion and dehydration. Ray J had just returned from a quick, 32-hour round trip to China for business and when he landed he immediately drove 4 hours to Las Vegas for the awards show.