How long from spotting to miscarriage?

Courts

Hi ladies, I was wondering if anyone could share the timeframe from spotting to miscarriage? I have been spotting brown blood on and off since Tuesday (5 days). Last night I had some red blood in the toilet and when wiping. It was considerably more than previous spotting. However, this morning i woke up with nothing on my pad, and nothing when I wipe. I also had back pain/cramping last night. Wondering if this sounds like a coming miscarriage? I've spoken to my Dr and she said just to go to hospital if it gets very heavy.