I HAD to reply to this, because I went through the EXACT SAME THING at the EXACT SAME TIME!!!! It was at my 4th period, and I flipped, because I was feeling so great, and then I felt crash-like out of the blue. Same thing as you, I would have called myself 100% better for the month before that. I was so worried, because Ihad been feeling so great. I am due for my 5th period next Wed, and feel a little pms feelings today. It is so weird to have a few great months and then feel crappy again, its also scary because you wonder "maybe it wasn't the mirena after all". Thank you so much for your post, you're the only other person who has mentioned this. It's just so strage that it happened to us both at the fourth period! I hope the fifth is better, but so far I'm doubtfull