Hey:) im 15 years old, female - im not overweight, i m about 5ft 4 - a little unfit but i ve never been the sporty type and this is very recent - my heart s been going all crazy in the past week or so - i first noticed it last friday. It felt kinda like adrenaline - i was just sitting there - nothing had happened to make me scared and i hadn t been running or anything - it doesn t hurt when my heart does this - it may not even b my heart ,sometimes it feels a little more to the left, like a lung or something - it ll just start going all fast and beating really hard for a couple of seconds. It s really scary. I get lightheaded a lot and im tired all the time (i ve been like that for a couple of years) and sometimes get sick when i m on my period - it s really freaking me out - hope you can help!! Thanks:)