Bleeding

I know a lot of people post about this. But I have been spotting a bit in the mornings for a few days and today I had a significantly higher amount of blood. The Doctor said the light spotting was normal. I went dancing last night for the first time in a while and my lower back was killing me but I thought it was just the physical activity. Can physical activity make you bleed f you're out of shape or am I miscarrying? This is my first pregnancy and I'm about 7 weeks.