Could you be pregnant? Maybe it's just your body getting back on track somehow? I guess you are in the same boat as me with your negative HPT and my negative HPT...and I guess for both of us a blood test seems like an option!? Ugh, I'm just stubborn and don't want to get one done because I say to myself "well, what are the odds?" and I talk myself out of it.
I don't know what to tell you, but that is kind of odd. Good luck!