About Twice Every Year For One Week Anxiety And Low

About twice every year for one week anxiety and low mood hit me out of nowhere. This time it was probably due to pmt but usually it comes from nowhere. It can be very debilitating and I literally want to do nothing but sleep and be alone. I become a nervous wreck and find it hard to face the world. Is it anxiety? Depression? Simply pmt? What do you think and what can help?