I'm 22 years old female 163 cm height 63 kg weight approx. From 2 days I am facing palpitations, heart rate rises upto 155 while in rest and certain tightness in chest. I do not have severe pain in left side. The pain or palpitations do not get worse by doing exercise. I'm not fatigue or sweat unnecessarily. I don't pant while climbing stairs or walking. But I don't have a routine I usually have my tea at 1rs0 11 am and breakfast at 12 12 30 pm for past 1 year or more. I sleep very late at night and wake up late. I have health anxiety especially cardiophobia. I don't drink much water. 18 months ago my ekg report was normal and 2 months ago my ecg report was normal. I don't usually have smooth bowel movements. I take eltroxin 25 mcg for past 3 years. 8 months ago my tsh level was 3.50. Please tell me if it is heart problem.