I hear you! I have never suffered from PMS- breezed through my periods, pregnancies- everything! Then about two years ago (I am 47) I began experiencing that same terrible fatigue two days before I get my period. It literally feels like someone has pulled my energy plug! All I want to do is sleep- it feels like the early days of pregnancy. I love to exercise but on those days I just can't muster up the ooph to do any. I also get a terrible headache which now seems to hang around longer than it use to.
I have just been living with it. I dread it when I know I will be travelling at that time or have a big event that requires energy and focus. Just being with other people is exhausting.
I haven't done anything except tough it out-I tried progesterone but got lazy with it and it didn't really sem to help anyway.
So you aren't alone. Oh and I had all the tests too and everything is fine. When you find a cure let me know!!
And I really feel for you having this with a child in your life. I had my kids when I was very young and I often wonder how I would manage feeling the way I do now. Hang in there!
You think you're not ever going to be able to eat another thing, but alas, you will find yourself feeling strangely peckish around teatime. The more you eat, the more you want. That's the way it goes."