is going through a rough patch.

The legendary singer, 83, was forced to cancel two shows from his A Quiet Celebration Tour in Philadelphia this weekend as a result of "unmanageable" back pain, he shared on his Instagram page. He will also undergo a "minor surgical procedure."

"Regretfully, Paul must cancel two shows tonight, June 28, and tomorrow night, June 29, at Philadelphia's Academy of Music," the statement read. "Paul has been struggling with chronic and intense back pain. Today, it has become unmanageable and demands immediate attention. Unfortunately, we have to cancel these shows at this time, as we don't have the ability to reschedule them."

The statement continued, noting that they were not yet able to reschedule the concerts for later dates.

"Unfortunately, we have to cancel these shows at this time, as we don't have the ability to reschedule them. However, we are hopeful after this minor surgical procedure which has been scheduled in the next few days, Paul will be able to complete the tour as well as look into returning to make up these dates," the statement continued. "In the meantime, please go to your point of purchase or local ticket provider for a full refund."

Being back on tour was likely a triumph for Simon, who has dealt with significant hearing loss that's kept him off the road in recent years. Hopefully, he'll be back soon.

Related: How Art Garfunkel's Wife Helped Him With Private Health Struggle