It sounds like you are experiencing a crash. Most, if not all, of the women on this site have gone through it. Typically it happens right before your period starts. For most of us the crash is when some of your Mirena symptoms return (anxiety, aches/pains, depression, insomnia). I think it has something to do with our hormones attempting to re-balance. For me, I tend to feel quite a bit better during and after my period. Good luck.