Ovulation test, please help!!!

Victoria • TTC#1 RAINBOW BABY=) miscarriage around 6weeks June 2015. Struggled with ovarian cancer at age 17 only have one full left ovary and a small portion of my right ovary.
So I got off my period about a day or so ago but I'm still having that light brown spotting you get towards the end and I had sex yesterday also took an ovulation test and it was negative with just one line then to my surprise I took on a few minutes ago and a major surge has occurred. There are almost two dark lines , how is this possible that I'm almost ovulating when I'm still having that brown spotting from my period ending? Am I just ovulating extremely early? Any thoughts and btw the second line is much darker in person I couldn't get the camera to focus just right