Burning sensation early pregnancy?

I took a pregnancy test today and got a positive result, it seems like a pretty dark line and it came up right away. I have been experiencing burning and stretching sensations in my uterus which have been pretty constant over the past 3 days, no bleeding yet. I've had 2 mcs in the past so I'm very worried. Both mcs started with cramping accompanied with bleeding. AF was due 2 days ago so is it too early to be experiencing this? Thank you for any advice!