Ovarian cyst: positive urine, negative blood test

I took four different tests on four different days. Every test had a positive result. Celebration begins. Then I started bleeding heavily with intense cramping (5 days after my missed period).  I go to the ER for a potential miscarriage. After a blood test and ultrasound I was told I was not pregnant, but I had an ovarian cyst. The doctor told me he doesn't know why my home test would show a positive result but I am definitely not pregnant with the result of my blood work. Do ovarian cyst cause false positive test? Or did I get blood work too early? Is there a chance I could be pregnant?