Hi Floss
I have bad cramping and lower back pain for the first 8wks of my pregnancy. I mentioned it to my doctor as I too was worried but was told it is normal changes - your ligaments are softening and moving around and things are being rearranged inside you.

As long as you do not experience bleeding too then I would not worry about it. I think an ectopic pregnancy would be so painful you would know.

Wishing you a H&H pregnancy - and congrats.
T.