I feel like I'm dying

I just get this feeling sometimes that I'm -- going to -- die soon or have a terrible illness. I feel like my vital energy is ending. But I'm young and my health is good. I've always had anxiety, but it used to be social anxiety, which was way better than this, at least I felt good when I was at home or with known people. Now it's all the time, everywhere. I have this weird idea that I'll -- die from illness by the end of the year, and I do know it's nonsense, but then I think that maybe it's my subconscious mind telling me something or that by thinking that I'll create an actual illness and then I can't stop thinking about it. It's so tiring to have that on the back of my head all the time.