Anybody have similar pain?

So for 3 days now ive had pain which seemed similar to a uti, like a dull ache over my pelvic area. Sometimes it feels like period cramps, and then sometimes it feels like Im just really constipated or I pulled a muscle in my lower back. It gets worse when I lay down, and feels a bit better when I sit up or walk around. When I lay down it feels more similar to period cramps, and radiates to my inner thighs. Im really confused as to what this is, especially because the pain is always changing. Ive had utis before and they've never felt like this,  and had my urine taken a few days ago so i know it definitely isnt that. If anybody is able to help me that would be great. Im 25 weeks by the way. :)