Hi KalEl - I just wanted to let you know that I too, have recently started to experience these exact feelings and I know just how scary they are. I think all we can do is just keep telling ourselves that if we have enough insight to question these types of thoughts and to be able to recognise that we are just nit picking and over analysing everything that's running through our heads then more than likely we are just fine.
I don't know about anyone else but I often find as well that when I feel calm and relaxed, after a little while I start to feel worried about that and think, okay it's only a matter of time until the anxiety kicks in again... and then sure enough, it always does, and usually with these types of feelings...
Again, I'm sorry that you too are experiencing these awful feelings, I just wanted to tell you that I understand where you're coming from and really hope that you get the support you need.
lulu