pressure and pain?

I want to preface this by saying I'm a huge worrier when I'm pregnant.. I was the biggest pain with my first pregnancy and was at the doctor constantly.. I'm trying really hard to do better this time. So far I'm 26 weeks and I've been pretty good about dealing with things but the last few days the pain and the pressure I've been having is really starting to freak me out.. it's super low and gets to the point I feel like I can't even walk. I'm not sure if this is something that's normal and I need to get used to or if I should be concerned.. I did mention it to the doctor and he said it's fine but didn't really check to see if there was anything going on.. I didn't have this much trouble with my daughter so I'm feeling anxious about it. Has anyone else experienced this?