20 weeks pregnant short cervix

Deniqua

Had intercourse last night after we finished i went to the bathroom noticed bright red blood on the toilet paper immediately went to the er bleeding stopped They said nothing was wrong when back to the er this morning did an ultrasound they said my cervix is 3mm but it’s closed baby is very very active still & I’ve been put on pelvic rest for 7 days why haven’t they started me on any medication??