Head shivers/shudders

Rias

Hey ladies, so my DD has this thing that's a little concerning to me. She's been doing this for months now. Out of nowhere it looks like she's concentrating on something and then her head like shakes a little. Like as if she just got the chills. Its like a shudder/shiver. I don't know. I'm a FTM so I'm worried as hell. I brought it up to her pedi a couple if times but he said he didn't want to do any testing or anything. He didnt seem to concerned. Does anyone else's LO do this? What's going on. Thanks ladies.