Hello I Had Plain In My Left Eye For 1

Hello I had plain in my left eye for 1 day movement of the eye than next day slow losing my vision I went hospital for 9 days I had taken blood test MRI scan and all all came back negative they said I had toxoplasmisis why never show up in my blood test ? I can't see blurred out retina but I see side of my eye perfect ? I don't have cats and I rare don't eat meat