Yes Lara this happened to me too this past fall. Life was actually going along good with less stress than usual, then bam- I started having anxiety every few days then eventually every day until I had to go back on meds. After getting through the initial side effects of those, I am now feeling MUCH better. I have had anxiety in the past, but this time it was worse than ever and I'm not sure why. I'm in therapy and we are talking about possibilities, but I am a big believer in genetics and I know I am genetically susceptible to anxiety and panic as it runs in my family. I no longer get periods as I am 45 and had a hysterectomy last year (but I still ovulate), so I don't rule out hormones having an effect too.
I'm sorry you are going through this, but you are definitely not alone.