Willie Nelson is taking some time off and canceling a few upcoming tour dates because of a "breathing problem."

The 86-year-old singer apologized on Twitter late Wednesday, writing "I'm sorry to cancel my tour, but I have a breathing problem that I need to have my doctor check out." 

Nelson had just finished performing with Alison Krauss in Toledo, Ohio, and he was next scheduled to appear Friday in Grand Rapids, Michigan.

He added "I'll be back."

His publicist, Elaine Shock, said Thursday that Nelson is feeling better and is now only canceling six concerts. He plans to return to his tour schedule starting Sept. 6 with the Outlaw Music Festival. 

His tour is scheduled to end on Nov. 29 in Thackerville, Oklahoma.

Nelson canceled his appearance at the Outlaw Music Festival due to illness last summer. He also was forced to cancel several dates in 2018.

Music Review Willie Nelson
FILE - In this Feb. 6, 2019 file photo, Willie Nelson performs at the Producers & Engineers Wing 12th Annual GRAMMY Week Celebration at the Village Studio in Los Angeles.
Richard Shotwell/Invision/AP