Janet Jackson is returning to her "Rock Witchu" tour and -- finally -- revealing the mystery illness that led her to cancel a string of concerts.

Following two weeks of scrapped shows, Jackson was scheduled to resume her tour tonight (Oct. 15) at the Verizon Center in Washington, D.C., after a bout of migraine-associated vertigo. She is being treated for the illness, which is characterized by dizziness, imbalance and other symptoms.

"She's a world-class entertainer and needs to be at the top of her game to give her fans the show they expect," Jackson's manager, Kenneth Crear, said in a statement. "She's feeling much better and is ready to hit the road again to finish the tour."

Upcoming stops include Atlanta, Houston, Dallas, New York and East Rutherford, N.J. Jackson, 42, will announce new dates for concerts she postponed in Montreal; Boston; Philadelphia; Greensboro, N.C.; Fort Lauderdale, Fla.; and Uncasville, Conn.

She is on her first North American tour in seven years.