Everyone dies, my friend, and everyone has to find a way of coming to terms with that inescapable event.
The sensations you report are clear symptoms of anxiety and will settle as the anxiety does.
That's what you have to hold onto while your surf the wave until it breaks and ends.
Anxiety is very unpleasant and sometimes very frightening.
I've had three protracted episodes of derealisation and extreme anxiety.
Time, eventually, restores my emotional and psychological balance.
All I can suggest to you is that you're worried about going crazy, you're not going crazy, because crazy people usually don't know they're crazy until they've been diagnosed as such and are also usually not suffering symptoms.
Your symptoms are not dangerous and will do you no lasting harm.
Be gentle and kind with yourself, rest and eat well and try to focus your attention externally, instead of on your symptoms.
It may take some time before you feel well again, but you will. Find a good anxiety therapist and talk over your fears with him/her. Better out than in!