Mountain Sickness is a common thing while you are in the High Area Trek in Nepal especially if you take over 3500 m High area you might get many different types of Symptoms, it depends what kind of Herman and body function you have but generally, most of the Travelers get this following symptom:
Note: If you have some of these symptoms during your trip especially over 3500 meters you should go down that is the main medicine for mountain sickness and also you can use Diamax to continue until you get down to low altitude.