Implantation bleeding confusion. This.

I get my periods regularly. I track my periods on Maya app, and my period date predicted by it was 8th August. I started spotting on 8th August itself, but the flow is not proper, i.e. eggs didn't came out in the flow. I am sexually active from the month of May 2018,I never had sex before. I have protected sex twice or once a month now. I fear this spotting is implantation bleeding instead of my regular periods. I am confused because my regular periods lasts for max 3 days and there is a heavy flow on day-2. And on day-3 i am spotting nominal and don't even wear pads. This happens since 2-3 years. But this time I haven't found heavy flow on my 2nd day. Also I had fever for 2 days, a bit stomachache, nausea. I PMS on regular basis, thus this symptoms are okay with me. But as I checked online same are the symptoms for pregnancy too. Please guide me for this.