Advise please?!

AF is due in 4 days. I really have zero symptoms of her coming or of being pregnant. Today, I went to the bathroom and there was a small amount of dark red blood. An hour or so later, slight spotting on a panty liner and when I wiped, there was a bit of dark brown blood. Now I have slight cramping, but nothing major at all...more like gassy. Anyone experience this? Why dark red/brown blood. Is AF just on her way and starting out funny this time?