Try not to worry, this is not in your hands.You have to wait till your ultra sound!!!Brown spotting has become common in normal pregnancies. It is normal for hcg levels to rise and fall during normal pregnancies.
You should really start to only worry if you start to have cramps, bright red blood, back pain.If this happens then.Go to the emergency room via ambulance, that way the staff will attend to you immediately!!!
God bless