Really confused please help

I took a pg test 2 days ago and it said negative and this morning for some reason I decided to look at it again before I dumped the bathroom trash and it was a clear positive. I don't understand why it did that. I took another test after I seen that and negative again. I'm confused. Am I pregnant?? Or not?? Period is due in 2 days. Can anyone tell me if it's a evaporated line??