Travel sickness can be treated with just ondansetron or a similar anti emetic. Unless you have an underlying condition of an ear infection or labyrinthitis, or something similar, most of the issue with travel sickness is that it is paychosomatic. Get yourself checked by an ENT specialist, and if it still persists, try and distract yourself, or sleep. Maybe take small breaks in between if possible while travelling.

May be homeopathy medicine have it's permanent solution...