Discharge/cramps

So I started my period today (2 days late) and it has been excruciatingly painful since it started and it has been a heavy flow of brown discharge and not red like usual. I am concerned it could be a sign of a bigger problem/early miscarriage, or am I just thinking too much Into it? I've never cramped so badly before, nor has my period been this color and consistency before. Any advice please before I make an appointment with my doctor?