anxiety is dragging me to the bottom

Has anyone else experienced such extreme anxiety that it seems to pop up everywhere, and you can't relax properly? The problem is, I can barely even go to the store (my stomach starts to churn, haha), let alone do anything else. And I have to fly to another country soon, so I'm constantly thinking about it. And it's not just that; I've never been able to relax properly my whole life. I constantly feel like the world is against me, even though if a stranger talks to me, I put on a mask of optimism and friendliness (many people have said they wouldn't even guess I'm such an anxious introvert). Has anyone else experienced something similar?