why are they sending me home!!!!

I'm 38 weeks and 6 days and have been having regular contractions for 72 hours. They were ten mins apart and now they have been 8 mins apart since yesterday. I was told to come back if I saw any type of blood and I've been losing my mucus plug in pieces for a while now. Well yesterday I spotted a bit while another piece of my mucus plug came out. Im 3cm and 50% effaced and I still got sent home!! I'm scared and infuriated. What am I supposed to do here?? 
UPDATE**** contractions got closer together coming 3-4 mins apart but not much of cervical change. Except a bit of extra thinning yet I was still sent home😩😩. Will be seeing my doctor today and hopefully we will be discussing my options if I don't have my baby in the next 4 days.