Nightmares and Night Terrors

My three year old has been having nightmares for quite some time. I think she's had a few night terrors as well. The other night she had night terrors throughout the night that were terrifying to ME. She was screaming (to the point she was choking), kicking, and shaking the likes of which I haven't seen for 15-20 minutes a go. I was ready to call 911 at one point. In the light of the day after it was over, I realized (thanks to a little extra info from healthychildren.org) that she was having night terrors. I'm grateful my husband held me off from calling 911.:) I feel like I was more concerned because she has had a febrile seizure another terrifying event for parents, but somewhat common and not anything to worry about (in and of itself). I know that both of these things are not harmful to kids, but in the moment...it's hard not to be overly concerned. Why didn't anyone tell me that terrifying moments filled with worry are a normal part of parenthood?