OP, from my own experiences in working my own feelings and thoughts, I wish to share this with you. This stuff may sound crazy but I assure you it is not. What you are afraid to face within, is where insanity is born.
The thing to understand is that you are holding a feeling-thought which is triggered. Say to your mind "mind, I know this is not real, it is a game, and I don't want to be afraid of this anymore." Understanding how we affect ourselves is key. Your body is responding with a sickly feeling once the deeper feeling-thought (belief) is triggered [psychological in nature; seeming a real threat but is not at all].
Note: Feelings have a thought counterpart. You feel something, and then assigned a thought to it (which has become a subconscious belief). While adressing beliefs in and of itself is relatively simple, without addressing the associated feeling, even beliefs can be difficult to let go of and/or change.
Something you can work with, and this is helping me also. A simple practice to allow suppressed feelings to emerge and be released.
1. Choose to have the courage to allow feelings to emerge that you have been surpressing (for whatever reason/s).
2. When you feel it, ask yourself "what a I feeling right now?" (ie fear, anger)
3. Now, allow yourself to feel it (rather than suppressing it out of fear, or perhaps considering it wrong/bad/weak etc to feel this way)
4. Ask this feeling "what is the message you have for me?" Listen to the answer. Your emotional intelligence is expressing itself and is worth listening to.
5. Choose to let go of the feeling now.
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Hopefully some of this may be of assistance to you. The inner workings of self can be mysterious until you begin looking within to understand what's really going on. In short: illusions; and we can scare (fear-full) the bejesus out of ourselves with our imagination, or otherwise (ie joy-full), depending on how you are currently configured to function (this means, what you believe about you and Life, and to be sure there are many beliefs operating within your subconscious mind, most of which have been forgotten about, yet are still in full operation within)