Lower back ache?

Louise
I found out I was pregnant yesterday very strong line. Approx 4weeks 1 day so early days yet! 
I unfortunately suffered an early miscarriage a few months back and because of that I am getting really paranoid. 
I've got some very minor and mild lower back ache - I'm probably looking for it due to last time!!! But can this be ok? Can it be normal?
I'm dreading the toilet every visit in case I wipe and blood starts :(