Is my scale broken?

My scale seemed fairly accurate until the last couple weeks. It is an older scale, I think I have changed batteries on it at some point when I had a long break from using it and then it wouldn't turn on anymore (if memory serves me correctly)
It was showing a fairly normal rate of loss from July 11(225.4) when I first weighed in when I started to work towards losing again. The first couple weeks it was showing around 3ish pounds weight loss and then it slowed to 1-2 ish pounds a week since.
Then last week my weight pretty much stayed the same (I weigh everyday). It hopped up and down a little bit (within a pound) but ended up the same weight at the end of the week that I was at the beginning of the week. I chalked this up to time of the month and holding onto more water weight.
So August 26 I weighed in at 211
then the next day my weight dropped to 209.2 and I thought I had finally started to lose the water weight from time of the month. Weighed that 2 days in a row then had another drop to 208.2, the next day 207.8, the next day 207.4. I did go up a hair the next day to 207.6, but then this morning I was 206.2!
That's 6.4 pounds down in a week and a day. Is my scale broken/running out of batteries? or what's happening? I know I'm quite heavy so have a lot of weight to lose so sometimes it can come off faster than when you just have a bit to lose, and if it was just water weight I was hanging onto the week before it's maybe not as huge of a loss but it's still over 3 pounds per week.