Self-doubt from last 6 years. In life.

I have deeply rooted fear that someday my intelligence/talent will be lost. The reason being I failed in one of the medical entrance exam which I was preparing with one year education gap.I always used to do best in studies. Everyone was hopeful towards me. But I failed in that. <LONG STORY HERE> Hence during one night I kept pressing my teeth on each other and then suddenly I heard some voices back of my mind. I was scared & thought something is definitely wrong with my brain... Now. I have a long story to tell. I abuse bad words inside my mind. bcoz by abusing I feels like I can control my intelligence. I just need a doctor who assures me that there is nothing wrong with my brain. I kept this doubt within me for very long time. I need a doctor who patiently listen to me and non-judgmental. I use this story as an excuse to not try something new. But now I want to get rid of this thought process. This self doubt is had lowered my self respect & I lost many  opportunities in life.