Last month 7 days before AF was due I got brown spotting and cramps like I was coming on. Nothing happened, 4 days later (3 days before AF was due) I took a test and got a faint line, that was easy to see IRL but quite difficult to photograph unless I inverted / HD it. (Photo attached)
I also had headaches for a couple of days, I’ve never had a headache before in my life, I just don’t get them. We got quietly excited.
The next day AF came, stark negatives ever since 
(obviously I’ve stopped testing now)
I’m not sure whether it was a chemical or just an evap line and AF arriving 2 days early?
Not that it really matters either way now but I’m curious!