Possible Clues:

• Prissy MP to marry, concealing sign all's not well
• Doctor's clue
• Patient's complaint, to a doctor
• Runny nose or headache, maybe
• Illness ID
• End of May marks beginning of pandemic in most unusual sign of disease
• Feature of disease
• It alerts one to illness
• Troublesome sign as extremely squiffy politician takes to motorway
• Tommy's quiet, possibly a sign of illness