Allegiant Flight Forced to Take Sudden Evasive Action to Avoid Mid-Air Collision, Injuring Flight Attendant

Allegiant flight had to rapidly ascend 600 feet after automated alarm about aircraft at same altitude.
Injured flight attendant hit her head and snapped her wrist; passengers experienced fear and panic.
After the sudden upward movement, flight attendants fell and passengers were crying and praying.
The flight returned to Fort Lauderdale due to injured flight attendant.
One passenger opted to drive home instead of getting back on a plane after the incident.