What Causes Light Spotting, Abdominal Pain And Brown Discharge?

I woke up this morning with bright red blood when I wiped after doing a wee - it seemed to go away then I discovered clear discharge streaked with blood. This went away for a while and I'm now spotting with some abdominal pain and a brown discharge was there when I went to the toilet a few minutes ago. I finished my period 2 weeks ago. My mum says this is nothing to worry about... What could it be? I've had bad kidney stone issues all my life but this is not something I've ever experienced with stones?