No heartbeat after hearing it 2 days prior

I had my first OB appointment on Tuesday, 10/9. I had a TV ultrasound and heard a heartbeat of 159. I should have been 8w1d based on my LMP but was measuring 7w1d. The next evening I experienced some red bleeding after trying to use the restroom. I called my doctor the next morning and was seen on Thursday, 10/11. The baby was measuring 7w5d but there was no heartbeat. They are convinced this is a miscarriage. I go back in one week for another ultrasound and to discuss options. This will be my 3rd loss since May. I still have nausea and sore/full breasts. I have had no further bleeding since Wednesday night into early Thursday morning.

Maybe this is a long shot, but has anyone ever heard the heartbeat, then not, but found it again? I feel like I’m experiencing denial.