Positive test, and now all negative test !!

Ti

I got one positive test this past Sunday and I've been testing almost everyday since and getting negatives... I've heard a positive is a positive but is there a possibility I got a false positive ? I've heard they are pretty rare and I read the test in less than 5 minutes. I have two apps for tracking and the one I've been using longer says I'm due for af in three days but as of right now I am on cd 57 and I've only ever gone up to 51 before