Hormones can bring you right to the edge and then keep you there for a day, without any outside triggers. Then all it takes is the smallest thing and...meltdown.
To people who say, "PMS is no excuse for bad behavior" (not specifically you, Fnord!
) : Imagine whatever your meltdown triggering overstim is, like a repetitive sound that won't stop, a sharp underwear seam, whatever. Now imagine feeling it throughout your entire body...for hours...nonstop at it's maximum intensity. PMS can really throw out of balance everything from serotonin to oxytocin & all the other hormones & neurotransmitters that help people keep their behavior socially acceptable.
To the OP: Due to an ignorant endocrinologist, I understand how badly hormone shifts can mess you up (and that's only half of PMS). But, it's a bad situation all around because the people around you IRL aren't likely to give you a pass. If you know you risk going into a meltdown, stay away from situations where it will have lasting repercussions. Put your phone away. Stay home. For that day or three, let people close to you know that you aren't feeling well and then hunker down and avoid as much human contact as you can, for you own sake.
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“For small creatures such as we the vastness is bearable only through love.”
―Carl Sagan