I took a pregnancy test and it was positive and the next day I started my period,

I took a pregnancy test and it was positive,a real light pink line,and then the next day I started my period.I didn't think that I misscarried because I know what those are like.could I have a positive test and it become negative?is that possible?Should I go get another test?I have had no cramping what so ever.I had one baby before and bled the first 3 months.I ended up having a cist but my baby was fine I just would have actual periods with her but with no cramping.Maybe thats it.I'm lost on what to do.Thank you,Emily