I Was Recently Walking Around A Campsite When A A

I was recently walking around a campsite when a a German Shepard came out between an opening barking like he wanted to kill me. I am petrified of dogs. I froze in sheer panic. I felt three violent racking shakes in my chest and my vision grayed over for a few seconds before I regained my sight. I did not faint but I felt like I was very close to it. My friend just kept repeating to me that the dog was on a leash. Should I be concerned about what happened?