My niece’s seizures

AB

Hi moms, asking for my almost 2 year old niece. She was on the plane and had a seizure. All the tests so far come back normal. Not sure what all the tests my sister in law did but she said docs said she’s fine. BUT, she gets a seizure every time her body temp is above 99. How can this be normal ? She has an appt to see a neurologist soon but I’m just in here asking to see if anyone’s baby ever experienced this. TIA! She was a premie, not sure if that is related to that. Also, forgot to mention that doc also said her head is growing a bit too fast so her tiny body can’t support it so she can’t walk in straight line. All these seems so scary to me. She’s almost 2.