Muscle or abdominal?

So since yesterday I been having like I don’t want to say “pain” because when I am standing up it doesn’t bother me. But usually I have like a muscle hurt type of “pain” in my lower abdomen. I am 21 weeks pregnant, but it feels like a muscle pain not like an inside thing idk how to explain it. Does anyone know what it is? It’s kind of uncomfortable, like when I am dressing and I am putting on my jeans or something it bothers me to lift my legs but is like a muscle/gym bothering. Like sore type of.. Lol any ideas?😅