Thank you for your query,
The prolonged vomitings almost 2 years duration should be evaluated further to look out any organic or nonorganic cause.
The vomitings associated with the traveling is due to motion sickness
as some children develop vomitings associated with vestibular system
dysfunction. This children can be treated with oral promethazine
half an hhour before the start of journey.
Anothe possibility to rule out is cyclic vomiting.
Monitor his weight and height in a growth chart
to look for any dip in growth.
So consult your Pediatrician
for evaluation and be in regular follow up till the diagnosis is made.
Hope i have answered your quey.