Remember, first of all 'the flu' is a symptom, not a disease. Detoxing is your best option. First take a hot bath with either Epsom salts, or apple cider vinegar.
Next consider the the symptoms, there are plenty of tonics that have been shared here on 8kun which can be looked up in the https://qresear.ch/ archive, doses and everything.
Goodluck and God speed to your healing.