Bleeding during first trimester

Anyone have redish brown bleeding /discharge with right side abdominal pain and have a successful pregnancy? I went to the er and they said it was too early to see anything on ultrasound but I did have a positive blood test. They didn't know what was causing the pain, sending me to obgyn in a few days. I'm hoping someone can give me a bit of advice on what the pain would be caused from. Plus they did check my appendix and no problems there. I'm trying to stay hopeful but know it could end in miscarriage.