Breathing track problem. Please help me.

From past 4 months I have this problem. It was the time I was about to write my tenth standard final exam and one morning when I woke up I started feeling very scared and i saw a difficulty in taking breath. But this thing continued and when I would be studying I could not breath properly. Then I thought it may be exam phobia but after I completed my exams in April 2016 I was still unable to breath properly. The other thing is I also start feeling a sort of scared along with this breathing problem. And if I run only a 20meters also I feel breathless and very much tired and overall I have dry cough since 2 months. Doctor please help me because I am not understanding what is the relation between breathing and this scared like thing which has continued right from my exam days. please help me.