The singer, who was forced to pull out of the Benicassim festival in early July, revealed that she actually felt the injury happen.
"I actually felt something go pop or snap, or whatever," Welch told Us Weekly. "Whatever it is, it was very frightening. I had to really adjust because it happened in the middle of a show."
She went on to say that she was checked out by a doctor after the injury occurred.
"I had a full check-up and he said that there wasn't any permanent damage that couldn't be restored without rest. So if I keep taking care of myself there won't be any reoccurrences."
Welch returned to the stage over the weekend, kicking off her North American tour in Vancouver on Saturday (July 21).