7 weeks 6 days intense cramping and spotting

Hi ladies! So for the past couple of weeks I’ve been having brown discharge as well as intense cramps. I had an ultrasound snd the baby looks great but the cramping and discharge came back with a vengeance last night into today. My doctor keeps saying as long as it’s not red/pink discharge not to worry but I can’t shake this feeling something isn’t right. The cramping is consistent but comes in waves of major intensity in my lower abdomen and back. Has anyone experienced this?