6:42 AM PT — A rep for Gladys Knight tells TMZ … she came down with the flu last night before the show and was treated in Florida. She was released overnight and is currently headed to her home in North Carolina to rest.

Gladys Knight has caught the bug and was forced to cancel her show in Florida over the weekend.

Florida Theatre President Numa Saisselin delivered the bad news at the last minute ahead of GK’s Saturday night show in Jacksonville. He says Gladys and one of her staff members became sick backstage at the venue and had to be attended to by Jacksonville Fire and Rescue. He says Knight “was smiling and in good spirts when she left the building.”

Theatre officials have not yet determined if the show will be rescheduled or not but said they should know by early next week. “If you are unable to attend a new date, as long as you purchased your tickets from the Florida Theatre or FloridaTheatre.com, we would refund your purchase,” they said.

We’ve reached out to GK’s reps to get an update on how she’s doing … so far, no word back.