Hello Hello Everybody My Question Is I Have A Positive

Hello hello everybody my question is I have a positive pregnancy test twice and it's it's positive but when I go to when I go to my OB/GYN he told me that I had to undergo blood test to be sure that I am pregnant but the result is negative she told me to just take duphston for five days twice a day and my blood drawn I'm not pregnant but my blood doesn't out I am pregnant is it possible to have false alarm in pregnancy test and is it OK to take the Duphaston if you are pregnant this in just 4week and 3days