Hello, My Son Just Woke Up With Severe Left Shoulder

Hello, my son just woke up with severe left shoulder and neck pain. He said the pain is underneath his shoulder blade from about the middle of his back up the back of his neck. He can barely move his arm and neck. It is very painful to touch, or move his upper body. Not sure what to do. He said he has not lifted anything heavy, he has not fallen down. Advice?