The headache and upset stomach are considered to be caused by two things.
Firstly, it is caused by acute gastrointestinal flu. Due to the combination of flu headache and stomach discomfort, the main reason is the presence of bacterial or viral infection in the body, it is recommended to check the blood test first to clarify the type of infection before treating it symptomatically; secondly, it is considered to be caused by plant nerve dysfunction, which is caused by the imbalance of sympathetic and parasympathetic nerves. It is recommended that the cause be actively identified and the nerve function be adjusted to relieve the symptoms.