It seems to me like you have become conscious. The ancient Tao used to smoke Marijuana to connect with the spirits. They believed that if you smoked for 100 consecutive days you will gain the ability to communicate with the spirits. Essentially they gained a level of consciousness from the plant that allowed them to feel the emotions of their sub-conscious. If a person does this procedure but without the goal of communicating with the spirits then they become aware of their subconscious and don't recognize it as something otherworldly, rather they awaken their sub-conscious which creates a feeling of unity in the mind. As of now you have actually reached a level of zen, but the fact is that when you don't purposefully strive for unity in the mind the silence inside yourself can be a very scary thing. You have a lot happening in your conscious but your sub-conscious is unused. Don't be scared of the silence and awareness. It means that you are discovering your true self; a place between the heart and the mind that is complete silence. It is the same silence discovered by the Buddha and by Tao. It is the silence that is you and not you at the same time. It is your complete mind becoming aware of it's existence by being conscious of itself and everything that it does to allow unity with the universe. If I'm not mistaken you might feel as though you no longer have a body. As though you are one with the universe. The silence and awareness you feel is just your existence, so don't be scared of it because it means that you are coming into yourself. The reality is that you have accidentally achieved enlightenment by realizing your body and your life. Embrace the feeling. Meditate on it when you are high and when you are not high. Find the powerful emotion in the silence and don't think. Just let yourself be clear and let the world melt away. You will flow down the river and become one with yourself and your life. The only fear is fear itself, so don't be scared of the silence and the awareness. It means that you have become yourself, not yourself, everything, and nothing at the same time. I've gone through the same experience. Not by the exact same means. It happened to me with a combination of psychoactive drugs and Marijuana, then every time I smoked weed I would feel the emptiness. It took me a long time to overcome the fear without guidance. Eventually I began to study Buddhism, Taoism, Christianity, Meditation, and Yoga. From that point on I've been able to see more clearly on all things and have began to change my life in a way that creates a perfect imperfection. If nothing else, when you are high, pretend that you are a zombie and do everything in your life as a zombie would. I don't mean stand in a corner growling, unless that's how you find zen in which case whatever, but be like a zombie with everything you do. Lose inhibition. Lose fear. Lose ego. Understand that the most delectable thing in life is a brain, and do whatever it takes to get brains. Don't go crazy and start eating people's faces on Miami freeways, but try to understand what brains really are and why a real zombie will always try to eat a brain at any cost. That's my advice to you. Keep smoking if you'd like. Quit if you need, but let the silence and emotion of the zombie take hold, and your anxiety will disappear forever. And I mean forever. Stay green ent-man!