Positive test yesterday, negative today

Becky • ttc
I took a pregnancy test yesterday and got a faint positive. I took the test yesterday in the mid afternoon. I took a test this morning using fmu and it was negative. I'm so confused now. I thought this mornings would show up because it with fmu. Same brand of test I took yesterday from the same pack (pack of 2) does this mean I am in fact not pregnant? Please help! 😔