period/obgyn

So I was a week late for my period took two pregnancy test both came back negative so I made an appointment with my obgyn and she also did a pee pregnancy test also came back negative. so I thought they would do a blood work one but instead she said she was going to "start my period" she did a pelvic exam, idk but what ever she did (down there) was sharp and painfull and then she said to expect my period soon.about 4 hours later I started my period but it's Not normal at all its a really dark deep red almost brown and seems more like a discharged then like a period and now I'm freaking out. I never had this done I didnt even know it was a thing for a obgyn to start a period I was so confused when she said that, she didn't tell me if this is type of bleeding would be normal she only said that my period will be starting soon.