Headache, nausea, stomachache, fever, weakness.

According to the symptoms you describe, it is likely to be a gastrointestinal disease caused by acute infection, such as acute gastroenteritis, gastrointestinal cold, etc. You'd better go to the hospital for relevant examinations in time to confirm the diagnosis. If it is acute gastroenteritis, you can take anti-infective drugs according to the doctor's advice, and pay attention to light diet.