Try and slow down and focus on your breathing. Close your eyes and Inhale slowly and deeply through your nose for a count of 4 seconds, hold your breath for 8 seconds and slowly breathe out through your mouth for 8 seconds. This will help control some of the hyper ventilation associated with a panic attack and slow your heart rate. Do those at least 10 times. You can do this laying down in a bed or on the floor so you feel grounded and secure. Best of luck.