OK so it all started with a slight chest pain. I went to my doctor and did a few tests and they said it was a normal issue. This pain then faded away but as I did , I began to notice that I was losing the ability to take a deep satisfying breath. At first I didn't really notice it but the horrible feeling just kept bugging me more and more. I went back to the doctor and reported this, I'm sorry but I can't remember what they said they thought it was but they told me to go to a breathing guide and to stop worrying. I never went to a breathing guide but I tried to practise deep breaths at home for a few weeks but it had no effect. 

The severity of it ranges all the time from me thinking I have had a 95 % full breath to a 65 % full one. But I do get a deep breath once every 10 attempts I would say

I have now been living with just this one symptom for 18 months and it is seriously becoming overwhelming because as far as everyone else thinks , it's in my head. I am a 16 Yr old male , who only rly has anxiety around this and would love anyone's thoughts on what I should do.