WWE has confirmed Sting’s injury. They posted the following on their website.
“Sting reportedly sustained an injury Sunday night during his WWE World Heavyweight Title Match against champion Seth Rollins. Check back with WWE.com for more details and updates on Sting’s condition following Night of Champions.”
According to PWInsider the talk going around WWE at the moment is that Sting suffered a neck or spinal injury. As of right now Sting is still scheduled to be at Raw tonight. If he is used at all on the show it will likely be a non physical role.