I had placenta previa with my first child -- two years ago -- and when the bleeding occurrences would happen, they generally stopped when the cause (ie, walking 5k or too much physical activity / lifting heavy items/ etc) was lessened/stopped. She seemed to have been dancing pretty hard core, but it's been what, a week now? The bleeding should have stopped.
I will say this, stress wouldn't continue the bleeding, from my experience.