Since you are bleeding you need to go straight to the ER. Just like Capriciousangel31 advised. I don't want to make you worry even more but your still in that scary time where miscarriages can happen. Also like the previous person said, every pregnancy is different. Go to the hospital to make sure you are not having a miscarriage.
if you started to bleed I would head to your local ER and get checked out tonight to make sure everything is okay.....as far as like headaches and backaches I hear each pregnancy is different so that could explain those