lower back cramps ?

Kelsea
Hey guys! 
I am 4 weeks and 6 days today . I'm due dec 13th . I woke up this morning with slight lower back cramps like a dull ache that comes and goes . My boyfriend and I had a miscarriage back in august and it nearly broke us I don't remember having cramps last time until I miscarried but these ones are just dull . Do you think I am okay? Is this normal?