Need advice

So this Saturday around 9 AM I took two pregnancy test back to back, they were both positive with two faint lines, then I decided to take one last night around 6 PM and it was negative I then took one this morning around 5 AM and it was also negative so I don’t understand how I can get two positives and two negatives? I’m supposed to start my period tomorrow but I have no symptoms of getting one. Usually by now I would be cramping and spotting.