So what’s going on

Took two tests they were positive pink and all it was faint and you could see it in good light and not really looking for it but after putting it down for a little and coming back it’s like I had to look for the line it’s like the test was now negative?!?! The test WAS POSITIVE within time frame it’s when I went back to show my spouse the test was positive it looked like the line had disappeared , and now all dollar store tests are negative so I’m confused