Oh the poor love!
Well I think there have been lots of suggestions here for possible causes.
If you're also unwell, then it could be that too. Aside from that, there are a few things you could 'eliminate' - throat/UTI, AF/pregnancy, other illness/teething, fast letdown - and then see where you're at.
With any luck it is a wonder week and you're through it soon. I think week 10-11 is a doozy.