Could this be something?

Rainbow • Ttc #1

My cycle ended the 3rd with the normal brown spotting (old blood)

I had sex that night, no spotting all the way until today. My back hurts and the blood is light pink?

I know my body is weird, I've been trying for forever lol so should I get my hopes up that this might be something? Or is it nothing? My back is hurting as well