For the past month or so ive had some symptoms which have gradually got worse. I'm 16 years old and im not on or taken any medication so cant be side effects from any tablets. First of all I've been feeling unusually tired, I have really low energy and have quit my hobby which I have loved for many years as I have just felt persistently exhausted. Also last night I was experiencing shortness of breath and chest pain this resulted in me having to take my inhaler for the first time in months, my inhaler helped with my breathing as my chest did not feel as tight, my chest pain was sharp and stabbing in my left side. As I was in the shower washing my hair I was finding it difficult to lift my left arm up as the pain in my chest was really bad. My skin has also been itchy all over, mostly my legs, arms, back and stomach. On my skin I have had a rash, the rash started as a red tiny pin prick dots, the dots last a few days and turn brown. I don't normally get rashes on my body so its a slight concern. I woke up this morning and on my left thigh there is a cluster of purple dots. I have tried to look online to see if anyone else has the same spots, I came across the name petechiae, however I am unsure my spots are these. My rash disappears and reappears in different areas and some are single red tiny freckle dots, when a glass is pressed on my rash, the red dot is still there and can be seen through the glass.

Other symptoms i have experienced: abdominal pain & dizziness

Has anyone got any ideas what could be causing all my symptoms? 

Thank you :)