That's the nature of the beast I'm afraid.
It will always try and get your attention one way or another and if you master one thing / symptom or learn how to live / cope with it, it will come at you another way.
Last week (after getting progressively better over several months) I was sitting at my desk and got this huge surge of fear coming right up from my stomach. That horrible gut churning feeling from out of nowhere. It was like my old friend 'Anxiety' was just letting me know it was still there, still trying to get my attention. I acknowledged it, the feeling passed and it was gone again.
What you have to recognise is the cycle - how your thoughts feed the feelings and round and round it goes. You went to the post office and you are home now. The task is done. But what's causing you so much panic and discomfort are the thoughts and feelings around it. It's not the going to the post office - you've done that. Acknowledge how you feel, rest if you need to, but don't agonise over how you feel - I tried so hard to go to the post office and now I just feel worse. It took so much effort .... It's not worth it, I feel so defeated, deflated, panicky, exhausted .. and round and round it goes.
If you haven't already done so, get yourself every single thing written by Dr. Claire Weekes. There are several titles and you can order them all through your local library or purchase them online even though they were written decades ago:
Self-Help for your Nerve
Hope and Help for your Nerves
Freedom from Nervous Suffering
Pass Through Panic
Essential Help for your Nerves
(I can't remember them all)
In the meantime, go on youtube and you will find several excerpts of her reading from her own books - play and replay these. Although her advice is 'old-fashioned' by today's standards, she still remains an icon to many because her advice is just so straightforward. She's been a life saver to me once again. I first became 'ill' with anxiety in my late 20s and decades later I've become ill again - probably due to a combination of menopause, my mother's death, relationship issues and just overwhelmed with work, kids etc. Whatever the reason, my world turned upside down last July. It came (seemingly) out of the blue and knocked me for six, and it's been a long, hard road to recovery ever since.
I am undergoing CBT therapy at the moment and do take Beta Blockers at night occasionally if symptoms becoming overwhelming.
But the thing that has helped me the most is good old Dr. Claire - bless her heart. Give her a go - she explains EVERYTHING.