What happens to Jaxson at the end of Chapter 14?

Dave and Donna from across the street come over to help Saskia get the air conditioning back on in the house. When Jaxson gets in the way, she tells him to go play with Zoe. Zoe comes and asks where Jaxson is. Donna sees him in the pool. She grabs him. He is taken by ambulance to the hospital, but everything seems to be fine.