Can drastic change from high elevation (2,000 meters) to sea level and from cold to hot climate cause flu like?

[jesusfoundme1604]

I recently traveled from the Mountains of North Eastern India (Darjeeling) to Hua Hin, Thailand. A little bit before arriving I have flu like symptoms such as fever, fatigue, upset stomache, and strange pains throughout my body. What can I do about this?