Anxiety when kids are sick

Hi mommies. What I'm feeling right now is probably anxiety. I always think of worst case scenarios whenever my kids tell me something hurts. I asked my 5-year old if something is wrong because he is so quiet and told me his chest hurts a bit. Then later he told me he is a bit dizzy. But now he is full of energy. I am feeling nervous right now. My anxiety was triggered and already thought of different bad scenarios. What do you usually do you calm yourself?