what does it mean if you get a positive test result then a negative result the following day?

Did an early test yesterday before period is due got a weak positive 2nd line. Did test today and got a negative result. So confused and upset. Can anyone tell me what this means? There was a tiny watery brown smudge on my panty liner last night. Still getting all the symptoms of pregnancy so I'm really confused my heads all over the place. Am I pregnant or not? Help please.