37 weeks brown discharge?

Last night my SO & I had sex, afterwards I went to the restroom and wiped and there was a tinyyyy bit of light pinkish blood, but I thought it was just from friction. This morning my hips have been killing me and I just went to the restroom to see this in my underwear. Anyone know what it could be from or if I should worry?? Baby has been moving this morning so I know she’s okay