15 years old, fast heartbeat and breathlesness
I am 15 years old and very scared. Just recently I have noticed that my heart beats very fast after little exercise. For example when I walk up the stairs I can feel my heartrate shoot up and my heart starts pounding. I also get out of breath very easily after minmal exertion. I used to be very active and take part in many sports but this fast heartbeat and shortness of breath are stopping me from doing a lot of sport. I am not sure how fast my heart is beating, I have tried to count my pulse but I am not sure if I im doing it right. I have found it easier to place my hand on my chest over my heart and count the beats but it is so fast I loose count. I ran up the stairs about 5 mins ok and I am still out of breath and my heart is racing. Please help me, I don't know what to do?