Should I call and go into assessment unit again?

I went into assessment unit last night with light bleeding. I thought it maybe because I’m o- and need another anti-d injection. They checked baby with doppler (156bpm) and my blood pressure. I had a pap smear (cervix was closed just had a small amount of watery-blood loss), did swabs and took bloods.

They asked if I knew the position of my placenta, I was told I had a low lying placenta at my 20wk ultrasound so they looked at the scan report. I had another ultrasound and had another anti-d injection, and sent home. Apparently this is common with a low lying placenta 🤷🏻‍♀️

This morning I’ve been having brown discharge, old blood I assume but not sure if I should worry or not. Opinions what to do?