How do you know if it's anxiety or something else?

I can't just be running to the doctor with eery scary symptom. Yesterday I felt faint, it scared me and panicked all day. Thought about going to the doctor but felt better later in the evening. Now Im afraid of haing scary symptoms again this morning and I might not be able to get my groceries again.

The drs I visited until today always mentioned that if it was serious, I would have symptoms more severe and constantly. They say it is almost impossible to miss a red flag symptom. They say, one would tell the difference.
Another thing, if I am having my on and off symptoms for a loooonng time and still alive, lol, that's how I understand they are anxiety.

But of course do these work all the time? NO... That is the problem with our anxiety issues.