She rubs her back a little, trying to comfort her-honestly, it works a little-Pearl gives really good hugs. Even though she can't talk, she's trying her hardest to just show Delilah all of her love and support
"What-What's wrong..did..did I do it..? I-I-I'm s-sorry I didnt-I-I couldn't-what..what did I do-I-I did something..what-what is it!"
She starts hitting her head, trying to think of it. Her mother taught her to hit on her own head if she did something wrong and well that's what she was doing, then pulling her hair became something to so she started pulling it too.