I have a little problem would love someones help please?

the doctor put me on the contreception pill yasmin on monday as that was the day my period started but i finished my period by the tuesday and i have been having troubles with them being really heavy and long. i have been fealing really crappy for 2 days but didnt no weather this was the new pill i was taking. but remember feeling this way during my first prgnancy. so i did a test and it showed up possitive staight away but then for the next 3 mins started faiding to alomost you couldnt see it but can still see a faint line.my question is could this be the pill that has made this test do this. please help.