Tmi- no pic

Hi I hate to post this but whenever I use the toilet for a #2 when I push even a little bit I feel like what I can imagine a contraction feels like. Very painful, kind of like a period cramp but further in. Goes away after 30 secs if I stop pushing. Ftm and only 21 weeks. Had an appointment today(forgot to bring this up as it had only happened once then) and my girl is doing just fine. Just hoping this is normal and has happened to other people. And by pushing a little bit I mean a tiny small bit.