Diamondbacks manager Torey Lovullo said the severity of Weaver's injury wasn't immediately known.
"We're going to obviously continue to evaluate him,'' Lovullo said. "He may be potentially a little banged up right now. If that's the case, it'll be an opportunity for somebody else to step up.''
Weaver said he left the game for precautionary reasons. He felt the cold weather might have been a factor in the injury. Arizona had a 6-1 lead when he left the game.
"With the conditions, and how the game was shaping up, I just felt like in my best interest going forward, play it safe,'' Weaver said.
The 25-year-old right-hander said he experienced discomfort throwing his changeup. He felt his mechanics were a bit off.
"I felt like I was rushing, so sometimes you just put your arm in a spot that's just a little bit funky,'' Weaver said.
Weaver has a career-best 3.14 ERA in 57⅓ innings pitched this season.
The Associated Press contributed to this report.