I'm sexually active and i started spotting light pink cm 10 days after my period ended. i also believe that i ovulate early based on what my app says. what could be the reason for this because i don't usually spot at all?

It happens sometimes: Many women have occasional variation of their mucus discharge, some spotting between periods, a heavier period, a lighter period, a longer or shorter period, or even a missed period. Having one or two of these symptoms doesn’t necessarily mean there is a medical problem, but a visit to one’s primary care or Ob-Gyn doctor is a good idea if symptoms are persistent, recurring, or worrisome.

Several causes: Women can sometimes have spotting around ovulation time (the time you reported having the spotting), but in any sexually active woman there is always the possibility of infection or pregnancy. If your period begins on time & you have no unusual pain/fever/discharge it is probably a normal variation, but see Dr if any of the above symptoms occur. If period is late, do home pregnancy test