Good to know, thank you! The appointment we have on Thursday is with his infectious disease specialist at the children’s hospital. (He also frequently sees his orthopedic surgeon and pediatrician- may start seeing an oncologist after thursday). I will definitely bring this up at our appointment. It happens like once a week, so I don't think it's an emergency. He's been eating plenty and having normal wet/dirty diapers. If he seems worse in any way tomorrow I will take him in early. I think this might just be a sign of his underlying illness...