The longtime staple in the wrestling community shared the medical scare with his social media followers ... saying the trip to the Norman, Oklahoma facility was "unexpected," but provided no further details.

Ross has dealt with numerous health issues over the years ... including an ongoing battle with Bell's Palsy, skin cancer and, just months ago, surgery to remove a mass from his hip.

Despite all the struggles, he has continued to hop on the mic ... most recently participating in numerous events for All Elite Wrestling.

72-year-old Ross rose to fame in the '80s and '90s ... making his debut with WWE at WrestleMania IX. He was inducted in the promotion's Hall of Fame in 2007.

He even made several in-ring appearances during his long stint with the company.

After his WWE contract expired in 2019, JR joined AEW ... lending his voice for Dynamite, Rampage and Collision.

We'll provide more information on Ross' status as it's made available.