Possible Clues:

• Influenza
• Flu, formerly
• Old name for the flu
• Understanding exercise, but still getting flu
• Old name for flu derived from the French “to seize”
• Complaint about onset of pain - 'flu, as before
• Keep on complaining about pills starting flu
• Flu, old-style
• One of the illnesses that are catching, you say
• Complain about onset of pig flu