For the past 3-4months I have been getting chest pains,below the lower left rib.Its a strong pain and lasts a few seconds sometimes longer.lately I have also been experiencing dizziness,to the point where I have to hold my self up with something.I am 14yrs,and do light exercise,but around school there is quite a bit of walking.I cannot sleep very well at night and cannot concentrate very well.I am starting my gcse s soon and want to do well,please help.