No Heartbeat Detected

I did my 5-Day ET on 18 June, did my HCG blood test on 30 June and managed to get a BFP with 670.6 results back. Did my first scan on 12 July managed to see gestational sac (measuring week 4) and yolk sac without fetal pole detected. I suddenly had brown discharge consecutively three days one week later and decide to drop by O&G and finally saw flickering fetal pole measuring approximately 2mm. Back for my scan today and no heart beat detected and gestational sac measuring at 5 weeks day 4. Anyone had similar encounter who can advise me? Thank you in advance! #firstbaby #pregnancy #ivfjourney