Pregnancy bleeding

I'm 12 weeks and started bleeding a little, it's gradually getting darker but not gushing or heavy. I've had some back pain which I saw as one possible symptom along with bleeding of a miscarriage. This is my second baby and I bled a little with my first also but I don't remember bleeding after 8 weeks. Any advice?? Is it worth going in or should I wait until my appointment in two weeks?