Little guy feels so low it hurts!

My older son was always high up. This little guy just moved head down this past week and feels so low. He moves in a way that makes me keel over and brings tears to my eyes it hurts so bad. It gives me cramps and searing pain through my pelvis. Doctor says its normal, anyone else experience this? I'm only 31 weeks and everytime I walk it happens. He does not seem to like me moving around lol.