One of the main causes of painful scrotal swelling is testicular torsion. This is an injury or an event that causes a testicle in the scrotal sac to twist and cut off blood circulation. This very painful injury could cause tissue death to the scrotum in a matter of hours. Medical conditions and diseases can also cause the scrotum to swell.
As said, credit and debit cards (cartes bancaires or cartes bleus) are widely used in France. This is also practical as automatic payments are common in France for things like train/metro tickets, parking, motorway tolls, etc.
The French Franc was the national currency of France until the introduction of the Euro in 1999 (in full circulation in 2002). Because France is one of the biggest and most stable economies in the world, other currencies were pegged to the Franc (especially currencies in protectorate territories of France).