Thank you for your query.
It seems like you are having motion sickness
due to the long car drive.
The headache, nausea
are the symptoms of motion sickness.
I advise you to take promethazine
in prescribed dosage.
Take rest till you get rid of the symptoms.
Eat soft food.
Drink plenty of water and oral fluids.
And consult your doctor for the prescription of the drugs for the motion sickness.
Hope I have answered your query.