I do have a doctors appointment Monday but I need help.

I am pregnant, early days yet not even 5 weeks.

I have started bleeding and am experiencing very bad back pain, not just in the lower back but its travelling all the way up to my neck and my left arm feels weak.

What could be causing this?

Edit: I have already called the doctors but they wont see me until Monday. They won't class it as an emergency because of how early I am.