 Or, maybe more accurately, I get scared of my own existence. 

I have no idea how to convey this, but it has been happening since I was  a small child, and it was significantly worse then. Basically, something reminds me of the fact that I am living, that I am thinking, that my consciousness exists, and I feel a sense of unease, unreality and panic. Moreover, whenever my mind goes into this, I feel like I can't breathe and that my chest is heavy. I feel 'trapped' in my existence, it's as if I get claustrophobic but from existence itself. The more I think about it, the worse the symptoms get and the more I get disturbed. I get panic attacks at least once every day because of this. I also have ocd breathing, which is probably one of the causes. I found distracting myself with other things to be the only way for this feeling to go away, but unfortunately, it comes back once the task is done and once I'm alone with my thoughts again.

What should I do about this? Did anyone else experience the same thing?