I'm 12 weeks pregnant. I did a lot of walking and lifting yesterday. I started having a heavy feeling in my abdomen, some back ache and leg ache. Today, I feel better but whenever I stand too long or try to do some work, I feel the pressure down in my abdomen/pelvic area. I don't have any other symptoms and no pain, just discomfort. And it gets better when I sit or lie down. Thank you! (this is my fourth pregnancy, I have 3 kids).