EXCLUSIVE

3:30 PM PST -- A rep for Prince tells TMZ, the singer has been fighting the flu for several weeks. He canceled 2 shows on April 7th but wanted to make Thursday night's performance in Atlanta, even though he was still not feeling well.

After the show, he got on a plane and felt considerably worse, so his plane made an emergency landing in Moline, Illinois, where he was taken to the hospital and treated. He was released 3 hours later, got back on the plane and is now back home.

Prince was rushed to a hospital early Friday morning after his jet made an emergency landing in Illinois ... TMZ has learned.

According to our sources, Prince's private plane made an unscheduled landing at Quad City International Airport in Moline just after 1 AM. The singer was immediately transported by ambulance to a nearby hospital.

A source close to the 57-year-old singer tells us he's been released and is doing okay. The nature of the medical emergency is unclear.