Hello. I am a 24 year old healthy female, and last week I started to not feel right. I felt that my heart rate was rapid and I checked it with the Nellcor (my mom is a nurse at a hospital and she has it to monitor pulse ox and heart rate). It would range from 90 BPM to 125 BPM. It would occur randomly and while I was just sitting watching television. Then I started to get migraines every day last week, and I couldn't go to work or to school. My doctor's office was closed, and so I decided to go to the emergency room. They did an EKG and they said it was normal, but they also said that my heart rate was high while I was there, but they sent me home. It has since gotten worse. If I walk up stairs, or if I exert myself too much, I feel lightheaded and my heart starts pounding in my chest, with this associated extreme pressure in my head. It passes after a few moments if I just stand there and breathe, but it I do not know what to make of it. Should I be worried?