S.B.
I have anxiety which stems from a traumatic event in my life. I had a hysterectomy so I can't relate any of it to my periods.
I agree with Erica. Exercise can be so good for you. You don't have to go to the gym or anything, but walking really helps me. Getting outside and breathing fresh air.
You can also try meditation. It might sound weird, but if you feel your anxiety rising, you can do breathing techniques. Also, stretching gently can help with muscles from being so tense. Can you sign up for tai chi at a local recreation center or something?
Exercise is free. You don't have to over do it, but you might find that "walking" things off when you're feeling super anxious helps.
I wish you the best. Anxiety can be managed. Hopefully you will find what works for you.