Could he be wrong about a miscarriage?

[Swband77]

I went for an ultrasound and was measuring 5 weeks 4 days and the heartbeat was 98bpm. My doctor said the baby implanted low in my uterus and scheduled me back for fetal viability. I went again yesterday for my 8 week ultrasound. The US tech first measured my uterus and everything. My husband said he looked at the baby for less than a minute and that the baby had grew a substantial amount and he could see red and blue light up but not sure if it was from me or the baby. He could see arm and leg buds and tell where the head was. I still have symptoms, mild cramping which I've had since week 3, and absolutely no bleeding or discharge. But the tech said he couldnt find a heart beat. He spent an entire five minutes in the room before leaving and coming back to call it a fetal demise.. He didnt let me see the screen or tell me how the baby measured or when he suspects the heartbeat had stopped. Is it possible he just couldnt find it? Is there a mean for worry? Should I get a second opinion? Anyone else experience this?