Im losing my shit!

Im freaking out. So this morning i had sex with my ex. When i got to work my period started but usually i dont get cramps (or whatever was goin on with me it felt like someone was trying to cut my uterus out like literally) just a faint cramp kindah like lettin me know its here and the same when its ending. So i went to the bathroom lets start off with the fact that it was brown n discharge like not even like blood .. so now im freakin out. I put a light tampon in wore it from my lunch break until about the time i got off work n it was barely even full. The cramps kindah subsided (i was basically in tears at work, i couldnt really breathe and i was gettin a headache) but now im scared everything ive looked up keeps sayin its a strong possibility i could be pregnant. Cuz my periods not technically soostah start for another 2 days. Has anyone else ever gone thru this ? I do have a dr appointment comin up before the year ends but im freakin out now! Lol

*Post Edit: i had sex 2 weeks ago right in the middle of my ovulation week .. forgot to say that my badd you guys