What Causes Brown Vaginal Discharge And Abdominal Cramps?

i had a cervical biopsy 3 days ago i also was swabbed and had my mirena coil removed since then ive had constant pain cramping on both sides really low down im not bleeding but have a dark brown discharge im also feeling very tired and low mood emotions im meant to be back at work tomorrow but dont know if i should go in as i would be standing for at least 8 hours