movement in my stomach but not pregnant

hey y’all, so i was laying down today and i felt this weird movement in my stomach. this isn’t the first time i’ve felt something like this, but usually it’s like little things. this was like something did a flip in my stomach. i haven’t had sex since may so i know i’m not pregnant. but the last time i did have sex, it was on the day i ovulated and protection wasn’t used (i got an iud 3 months later) but every test is negative so i know i’m probably not. it’s just sooo weird. does anyone have any idea what this might be?

i also keep having vivid dreams that i’m pregnant and in all my dreams i always say “but i have an iud” but maybe that’s just my mind lol.