Weird pregnancy thing?

First of all you shouldn't get nervous - it's not good for both of you. Feeling numb here or there is normal during pregnancy. Some of it might be caused by nerves entrapment in your lower back area (bones change position to make possible for baby to come out when ready), and some of it could be due to water retention in your body what puts pressure on the nerves. Baby is still too small to put any pressure yet.