ok here's what I'm feeling & I've never felt it before .this is my third child however the last time…

ok here's what I'm feeling & I've never felt it before .this is my third child however the last time I have been pregnant was seven and a half years ago so some things kind of feel new. I have this pressure pulsing pain down there especially when I walk. I went to the ER they said I was fine my OB said the baby is low by my pelvic area and there's not a lot of room down there any more for her so I'm experiencing pressure.the pain is hard to describe. any one feel this? 20 weeks.