Girls, how do you know when a child is in pain? Screaming, crying. It …

Girls, how do you know when a child is in pain? Screaming, crying. It seems like just calming them down and after 10 minutes they start crying again. Sucking on their thumb and crying. Putting it down - crying. Shaking it - crying. Crying even on my arms. I don't even know what to do anymore. There's no fever. It's not even hiccups. Legs aren't squeezed. They just scream and all, tears run like a river. My heart hurts.