Is It Safe To Take Progesterone Support To Avoid A Miscarriage?

Hi , I am pregnant in my 45th day , I Had polycystic ovary syndrome and was on metformin for a while and stopped it after I had sever brown spotting discharge 2 months ago. now I just known from my doctor that I am pregnant. I started to have this brown spotting again this morning. I am afraid to lose baby. Should I take Progesterone Support although Doctor said no need. I will be admitted to Hospital this night , what are my risks ? please advise !