So as I've been on the computer basically 95% of my waking hours the past 9 months and only ever eaten things like pizza etc I'm 16 and 6"3


I went for the *first time* in about 9 months for a one mile walk (I rarely even step outside once a week, let alone walk. So while I was walking I had very bad chest and back & stomach pain. When I came home to rest after that huge walk, it has taken me nearly 30 minutes+ to have a normal heart beat again and while trying to rest I've had head pressure and a little left arm pressure (very little left arm pressure) and also heart palpitations.

What could this be, I know I'm extremely unhealthy and extremely unfit, but is there something wrong with my heart now or something?