Sometimes I feel like my anxiety works on a spectrum. For me, it's not normal anxiety vs. a panic attack but a continuum where mild anxiety is at one end and severe panic is at the other end.

It does sound like there were some "panicky" aspects to your anxiety (if that makes any sense) and so I can understand why it was especially scary. Being scared of these new-ish symptoms probably only fed your anxiety and made it worse. That's what a lot of my anxiety is sometimes--anxiety about my anxiety.

I think my advice would be is to not take this as a sign as, "Crap, now I'm having anxiety at work that I didn't have before, something is wrong with me, something has changed." It was one instance. Maybe it will happen again; maybe it won't. But try not to convince yourself that this is a portent of worse to come.

Can you split the Xanax in half? (How many mgs are the pills?) Benzos make me tired as well.