It might sound stupid...but like try and make things comfortable. Like have a comfy blanket you can get cozy in, watch some movies or shows or even youtube stuff you like and/or play video games if you like any or read a book just anything that is a low effort pleasant activity. And drink some chamomile tea, it's nice and comforting.
Idk basically try and surround yourself with comfort items and activities that can help keep your mind off some of the worrying or whatever.
Also if you are having cramps you can try taking an asprin or tylenol to help that a bit, or there is that midol or off brands that have tylenol, caffine and an anti-histimine which can help that part. Idk I feel like a lot of my PMS is simply due to my insides hurting during that time of the month(like who wouldn't be in a bad mood from their body giving them pain?) so things to relieve that pain do lessen it.
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Eat the rich, feed the poor. No not literally idiot, cannibalism is gross.