What Is The Irregular Pink Discharge And Cramps After Having Sex?

hi i am 19 i think my perriod is regular but for the last couple of months in a row i have been commin on around the 26 me and my boyfriend had sex yesterday and i started feeling cramp around 11;00 at night and i started bleeding slightly , when ever i come on the first day it starts off pink then gets darker and becomes bright red, when i checked last night i looked like that im still bleeding now but im not sure if this could be spotting or the start of my perriod because i would come on around this time . but could spotting occur the same day i thought it was 6-12 days after conception i dont know what to do im realy scared