Tmi, bathroom stuff

Renee
So lately when I go to use the bathroom, when I poop and contract my muscles and all that good stuff I get this weird feeling in my lower stomach portion now I took a pregnancy test both were negative according to the app <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">period tracker</a> I'm suppose to get my period today and according to glow Im suppose to get it on the 29th and my ovulation date was the 12th I did use pre seed, I just need help has anyone gotten a weird feeling like this and if so what was the cause.