I am 19 years old i weigh about 145, pretty healthy. I just quit smoking to hope decrease my tachycardia which ive had for about a year. I have lost some weight and decreased my workout routines, and i would say ive been pretty stressed the last year. I have decreased appetite sometimes. My tachycardia appears every now and then and when im not doing anything physical. I get shortness of breath but if i take deep breaths it usually dissappears. Whenever im in a really cold room with a/c i feel shivering in my ribcages and increased heart rhytm. Its not just when its cold it occurs even when im warm but not the shivering. Somedays the tachycardia gets worse and gives me a minimal pain everytime my heart beats, (from a scale of 0-10, the pain would be a 3) and sometimes it doesnt hurt but just beats really hard. What should I do?