I have plenty of slump days. They aren't always quite as "perfect" as I wish they would be, but I've found that if I stop putting as much emphasis on the scale and start focusing on the days on plan that I can power through.
I have several "On Plan" challenges going on at the moment, and for those days when I really feel the tug of the old lifestyle ghost haunting I imagine how giving in will make me feel the next day.
It sounds like you're having a rough time right now.
And that can be really frustrating, because on top of the bad days... then the scale shows up to make it more annoying. It's possible that your focus should be purely on the days themselves at the moment.
Do you remember what a day was like when you first got into the swing of things? Did you plan your meals? (Or maybe you need to now?) Were you tracking vigilantly? (Maybe you need a change in how to track and trying a new method for a week would get you back into that new person/learning space?)
Maybe you need a challenge? Or a regular place to be accountable? Cheerleaders are great! But, sometimes (depending on the individual) what we really need is a drill sergeant. Someone who isn't going to take excuses or self pity. Someone who is going to raise a brow at our whining and kick us in the butt, tell us to go back to being an adult.
You're in a rut. So something needs changing.
You just have to try different things until something clicks!
By the way, congratulations on all your progress. =) Losing and maintaining at that weight is an enormous success! Keep at it. You'll find the key to move forward.