Possible Clues:

• Indigestion, Pepys said, needs treatment
• Poison sipped, say, upset stomach
• Brand of cola in off days produces indigestion
• Pepys said sadly it might be the result of unwise eating
• What are the odds of dryish fizzy drink leading to a tummy ache?
• Awful days wrapping broken pipes leads to upset stomach
• Indigestion from fluid sipped, say
• 'Upset stomach', said Pepys in distress
• Upset stomach, with bad days drinking cola
• Oddly, Pepys said, it could result from rushing courses