Didi,
I had the same exact issues....was dark purple for days then gradually started to fade even though I wasn't changing my menu. It was so mentally bad for me and discouraging that I quit the strips all together. I know I'm in Ketosis by my breath and also (I know gross) but the smell of my pee. I'm convinced my strips went bad because I kept them in the bathroom which is vry humid in our house. Don't let the strips dictate your sucess why they are a motivator they also can kill your motivation in an instant when you most likely are still in Ketosis. Give it a week and see if you are still loosing inches or pounds... Don't depend so much on the strips to tell you. Trust me i felt so much better when I threw those darn things out!