Rapper Post Malone postponed a concert Saturday in Boston and sought medical attention due to an on-stage rib injury he sustained in St. Louis a week earlier.

Post Malone, whose real name is Austin Richard Post, said he has experienced breathing pains and a stabbing pain, after he fell through an opening on the stage during his performance at Enterprise Center on Sept. 17.

After the fall, the 27-year-old singer-songwriter remained on the ground for a few minutes but was able perform the rest of his set.

"Today I woke up to cracking sounds on the right side of my body," Post Malone said Saturday in a statement.

"I'm having a very difficult time breathing, and there's like a stabbing pain whenever I breathe or move. We're in the hospital now, but with this pain, I can't do the show tonight," he added.

Ticket holders can apply for tickets to a future show, Post Malone said.

"I feel terrible, but I promise I'm going to make this up to you," he posted on Instagram.

"I love you Boston, I'll see you soon," Post Malone said.

Post Malone has been performing on the "Twelve Carat" Tour. His most recent album, "Twelve Carat Toothache" was released on June 3.