Very sorry to hear that you purchased a fish that was supposed to be treated but wasn't. A fish cannot be in infected and then show visible signs of Crypt in 24 hours. The part of the life cycle where it's visible takes much longer than 24 hours.
What YOU can control now is:
1. Aggression - keep an eye on any aggression in the tank and make sure the angel has a good hiding spot
2. Feeding - make sure to feed quality foods - fresh over frozen but high quality frozen will suffice - don't rely on just flakes
3. Water quality - make sure to keep the best water quality possible (water changes, don't over feed, reduce temp flux, etc.)