Nobody can figure out why the pressure in my head is so high. The last spinal tap it was 41. They also found an ovarian cyst. Could this be causing the pressure to be so high?

I had a blood test done 5 days before my period is due, and it was negative. That same day I found out that I have a cyst on my left ovary. Can an ovarian cyst cause a false negatrive pregnancy test?
My period is due tomorrow and there is no sign of it coming..