Girls, almost 13 weeks pregnant. Today I had dark brown spotting. Was …

Girls, almost 13 weeks pregnant. Today I had dark brown spotting. Was fine last week at the ultrasound, but today this is happening. So I lay down and am very worried. I'm thinking of how best to proceed, go straight for another ultrasound or see a doctor at the gynecological clinic?! Since there's no ultrasound machine at the clinic, it's unlikely that the doctor can determine the cause without an ultrasound... what would you recommend? Thank you ?