Back pain is normal. The bleeding does not always mean good or bad. I would definitely call your doc. and DEMAND they use either the doppler or give you an ultrasound.I am on the paranoid side when it comes to preg due to two previous losses, so I take no chances with anything. Fight for your rights with the medical system :) Good luck!
I agree with Joy. Any bleeding should warrant a call to your doctor.
Yes- sciatic pain can cause what you're describing. Anytime you have bleeding or spotting you need to notify your doctor.