Is bleeding during second trimester is normal?

I am still experiencing bleeding and spotting. I am 12 weeks and 3days old pregnant. Is this normal? I have a weekly check up with my OB but she can’t determine yet what’s the cause of bleed. All my test are normal and there is no sign of infection. Hope you could give me some advice. This is my second pregnancy last year i had miscarriage due to early fetal demise. I have a trauma already and I don’t have any idea what’s wrong.