Is there a reason you haven't rushed her to the ER?
I would definitely take her to the doctor ASAP. That is not normal for a 17 year old. If it's nothing to worry about, you'll know. You can't play around with chest pain, and hope it's nothing or that it will go away. Get her checked out.
IMO, I wouldn't be worried about this. Children and especially teens, have a tendency to have chest pains. The thing is that true, heart related, chest pains are never sharp as your daughter is describing. Also, there are only a couple of forms of heart disease that would cause true chest pains in young people and believe me, you would know there was a problem there because the heart disease would have had to progress to such a degree that your daughter would not be able to function on a daily basis; walking would cause chest pain that doesn't let up with rest. She would never be able to keep up with her friends and hanging out at the mall would be a nightmare for her. Sharp chest pains are usually caused by muscle problems. Fatigue is very common among teens because they lack the amount of sleep they should be getting. Even if you send them to bed, they don't go to sleep, most of them are up goofing around. The variation in the heart beat that you hear is called a Sinus Arrhythmia and is normal. It is caused by breathing. As a person breathes in the heart rate speeds up and as he breathes out, the heart rate slows down. True arrhythmias start and stop on a dime, literally. This happens as the electrical impulse "jumps" from the normal pathway to an accessory pathway and then "jumps' back to the normal pathway again. Your heart rate would be 80 and then 170 and then 76, just that fast. It would not be running 80, 96, 109, 129, 140, 155, 166, 170 and then back down again. The tingling down the left arm is something she may feel but it is likely that she knows the signs of heart disease and therefore feels that this is an issue. Most people with heart disease that have a problem with the left arm have severe aching in the arm, not tingling. I do not want to degrade what you are going through, but my advice to you (having lived through this with my own daughter who was transplanted at 22) would be to acknowledge the problem your daughter has, but to not make a big deal about it by listening to her heart. The more you show concern, the worse this will become and you risk turning her into a cardiac cripple; in the end, her friends will leave her behind and the results could be devestating for her. Take care
My symptoms for my heart attack were the same as your daughters. I'm not saying that they are the same diagnoses, but it is worth getting checked out. I had no clue that I was having a heart attack because my biggest 'pain' was in my arms-I wanted them cut off! Do have her checked and tell us how it went. I hope she has a good outcome