Postive then negative test

Ok first time posting just after advice please as I'm losing my mind I've done 4 tests this morning 3 different brands and 2 the same brand will post pics too but is it possible for a test to show a faint postive then dissappear?? af due in 2 days (Friday) major lower backache sore breast heavy and nipples on/off darkish thanks for any advise been trying again for nearly two years also have endometriosis and ovarian cysts got an operation 1st March xx