okay I'm really concerned about something. I'm 29 weeks. And my baby moves a lot. But randomly out…

okay I'm really concerned about something. I'm 29 weeks. And my baby moves a lot. But randomly out of nowhere I'll get this extremely sharp almost scratching pain inside my uterus underneath my belly button. like someone is scratching the inside of it really hard with their fingernails. it happens out of the blue and makes me gasp because it's so painful. does anyone else have this issue or know what could be causing it??