I never realized so many people here had this! I'm so sorry, it's hell. I don't have a diagnosis, as they like to imply it's all mental, but it is clockwork. Mood starts dipping around ovulation, providing I do ovulate, and it's all downhill from there until I'm completely dysfunctional, actively suicidal, and crying every single day or full of so much rage I get intrusive thoughts. Then I'm back to square one a few days into/after my period. It all depends. This disorder is debilitating and doctors will just scream "it's depression!" and send you on your way. Yet it can be physical, too. Endless cravings, fatigue, brain fog, aches and pains. Hormones affect so much of the body, yet there is so little research and answers.
Normally, I have a few days of feeling good, a few days of baseline mood, and then it all starts up again. Unfortunately, this month I didn't get my 'good week'.
Needless to say I understand. I feel for everyone struggling with this, and it's not in your head.