Period or pregnant?

So I just got a positive lh surge last Thursday (later than predicted...cycle day 35) and my period is predicted for today. My cycles have been ranging anywhere from 34-44 days. Since Wednesday I have been having back pain and lower abdominal cramping and today I’m having light brown discharge when I wipe. I never have back pain before my periods so I don’t know if I’m experiencing early pregnancy or if AF is on the way. Anyone else had a similar experience? How did it end up?