positive followed by a negative?

So I took a test yesterday afternoon and it came up positive. Within 2 minutes of taking the test a vvvvfl came up. Took a pink dye test and the feint line had color. AF isn't due until 5/8. Decided to test this morning with FMU and it came back negative no sign of a line. Has this happened to someone before? I'm waiting until AF is due to test again but I can help but feel bummed about this.