Period pregnant or something else?

I've been spotting brown for a good four days straight it's very on and off sometimes it's thick stringy and sticky and sometimes it's light and watery. The first night it happened I got a sharp shooting pain in my right ovary. I have that same pain now. I am supposed to get my period in 2 days according to this app. Has my period just come early and I'm freaking out or am I pregnant and this is implantation bleeding? I'm on birth control pills but I know sometimes it can fail so my symptoms are worrying me I took a pregnancy the first night I had cramps and weird discharge but it said no. I'm not sure if I took it too early.