Welcome to Healthcare magic forum,
38 kgs is very low wt, few tips u can follow to become healthy:
Eat more fruits and vegetables.
Avoid junk foods.
Drink 3 lts of water a day.
Take some good protein and vitamins
Check ur Hemoglobin
, if less start iron supplements
start walking for 30-40 mins a day.
do this for 2 months if still no improvement consult ur doctor for further evaluation.
Hope I have answered ur question.