The right-hander got hurt in the third inning of Friday night's game against Cincinnati. He felt pain while throwing a slider, but remained in the game to finish the inning after he was examined by a trainer.
"I have no clue what it is. I've never had this," White said Saturday before going for an MRI exam. "It's sore and swollen. We've been treating it -- ice and stuff -- but we can't really do much until we know what the problem is."
Manager Manny Acta said putting White on the shelf even before getting back test results was the thing to do.
"It's pretty clear," Acta said. "If you have to take someone out in the third inning the chances of him being ready to pitch in four days are not very good."
White said he understands the decision, too.
"It's a good decision, because it's pretty obvious I'm not going to be able to throw a baseball effectively for a couple days," White said. "Even after that, it's going to be a process to get back. Hopefully, it's not too serious and we can start throwing within a week."
Acta is encouraged by Sizemore's work on the sidelines.
"Grady is swinging the bat very well in batting practice," Acta said. "He's doing most of the activities that the last week or so were bothering him a little bit -- bending over and moving side-to-side and that. So we're anticipating him to be ready really soon."
To take White's roster spot, the first-place Indians recalled reliever Josh Judy from Triple-A Columbus. He was 2-1 with six saves in 16 appearances for the Clippers.
A first-round pick in 2009, White is 1-0 with a 3.60 ERA in three starts.