I have been having a lot of night sweats and cold chills during the day. so strange for me....

See an ID doctor: There are multiple possible explanations for this and the people who are trained to be clinical detectives are the infectious diseases experts. This sounds as if you are having persistent fevers. You chill when the body's thermostat turns up. This generates heat & you have fever. The body temperature is reduced when you sweat, as one of the mechanisms for losing heat. See an id doctor.