Hi can any one anwser this im 16 weeks pregnant today?

ive got a angelsounds fetal doppler the heart beat sounds strong and fast then slows way down the thooding one nose say it goes der der der der then slows down to der der der i dont no what to do as its friday evening here all midwifes that deal with me will now be closed and im sure hey wont give me a scan is this normal ?