I don't want to get excited too quick but could it be???

I started to experience pelvic cramping on my left side 2 days ago. I had no spotting no unusual discharge. The pain had started on the left and moved to my back. it wasn't unbareable but it was uncomfortable. This morning I had put a fresh pair of undies on when I woke up (I don't sleep with undies) a few hours later I found it was stained. I had a small fright and thought oh well here's AF but I ran the bath tub and when I had a bath I examined myself. No bleeding no spotting nothing. Could I really be pregnant?