If she had a very scanty bleed after an episode of sneezing then it's likely to be a trauma to the vessel which will heal on it's own but if there is a profuse bleeding which occurs multile times, I would advise you to visit an ENT doctor so that you can be examined and undergo the necessary investigations to find the underlying cause of the problem and have it treated accordingly.
Next Steps
Follow the steps as advised
Health Tips
If condition persists or worsens visit the ENT at the earliest