Shemo,
I have been where you are and there are times yet when I get tossed back into those same feelings of doom and "what if?" thinking. Anxiety can cause persistent and uncontrolable nervousness, stess, and worry that is triggered by anticipation of future events, memories of past events or ruminations over day-to-day events both trivial and major.
Like you when I have these intense feelings it intrupts my daily life.
My therapist helped me understand while we are worrying about dying, we are not living.
Do check out our resource thread at the top of this page and you will find many help ways to learn how to beat anxiety. CBT is extremely helpful. Remember you are not alone as we are here to support you.
Kindly,
Kitt