BFP then next day BFN?!

Yesterday at 10 DPO i got a faint BFP on a FRER. This morning I got stark with on FRER. So confused and gutted. I did drinks LOTS of water yesterday. I have no cramping or pain. AF isn’t due till Wednesday. Has this happened to anybody be else and it had a happy ending 😢 I had a miscarriage in January so hoping this wasn’t a chemical.