Brown discharge

Hi everyone, I am 6 weeks pregnant and have been having brown discharge on and off for a couple weeks now. No cramps or deep red blood. Has anyone experienced this? I went to my family doctor yesterday and there was a fill in for him. He immediately said I was going to have a miscarriage so I am suppose to relax and let it pass. I was so upset. Does anyone have any insite on this topic? Is it common?