Girls, has anyone had this? In my first pregnancy, it didn't happen, …

Girls, has anyone had this? In my first pregnancy, it didn't happen, but in my second at 20 weeks, I was having pain between the legs when I got up from bed. Now I'm 26 weeks and the pain is stronger, even when I walk. The doctor says everything's fine, but how can it be fine, as it hurts so much.