I posted this on MFD to a member who experienced a sudden, unexplained spike in her weight. I'm reposting here - because, well 1) I need to remind myself of this daily these days and 2) others may also need to be reminded.
Your frustration and it sounds like a bit of fear feels very familiar to me. I really do believe the spike on the scale is a temporary thing and that you should not let it cause you more stress. That is much easier said than done. Unfortunately stress will cause you to hold on to pounds. And you have been through some major life changes this past year. Good or bad life changes cause stress. It could just be your body's way of saying "I need a bit of a break"
That said, I think you are very wise to not just shrug and blame a hard exercise day, or sodium or hormones, or stress. That's what I did - over and over and over. And now I have 20 lbs to lose. I'd hate to see you go through THAT. Talk about stress!
I do encourage you to stay honest with yourself and GENTLY keep yourself on track. One thing I've noticed about myself, even at 20 lbs over weight - if I eat well and exercise, I don't worry about my weight. If I eat badly, I will worry about my weight and worry tends to cause me to eat badly. It's a vicious circle. My main point that I don't think I'm making very well - is to be gentle with yourself. Give yourself some slack. As long as you are honest with yourself and keep using the tools you have - you will get back to your happy weight.