False positive?!

Ashlee

I finished my period a week ago. Had nausea all day took a pregnancy test and it was POSITIVE, it didn't even take a full minute to show up....took 4 more and they all took the full 3 minutes and were negative. OB/GYN is leaning towards a false positive but it could be early enough that HCG levels were high enough for the first to catch but not the others. Waiting another week and taking another test. How could this be possible since I just had my period????