Admittedly I was over twice your weight but I've had 2 fairly large streaks of anxiety (I'm still in my 2nd one) and it really does rip through your weight.

The first one I went down 3-4 stone in a couple of months.

This one has been slower, maybe only 2 stone and I think I'm bottoming out (well actually I thought I'd had some good news on the health front - so I started eating have my doctor turn round and basically say ignore what you have been told, there could still be a problem)

Just don't end up weighing yourself, religiously, I was doing it 3-4 times a day and panicking when it dropped 2-3kg over a day (but ignored the fact that it usually went back up 2-3kg the next day)

It's nuts what anxiety can do for your weight, I'm about the thinnest I've ever been since I was a teenager, doesn't necessarily mean cancer (even though I have similar thoughts in my own head!)