So worried :(

Been a crazy day for me :( so I had a miscarriage in November so they have been monitoring my hcg levels, Monday my levels were 2906. I had some light spotting on Wednesday at 11pm, they did blood work at about 1am my levels came back at 3196 and they booked me for a ultrasound for this morning at 9 am. I was measuring at 6 weeks and they was a gestational sac and yolk sac but no cardiac activity. The ultrasound tech put on the bottom of the report not a viable pregnancy I burst into tears in the emergency room. The doctor saw how upset I was and ordered another blood test to check my hcg levels, three hours later the results came back and it had gone up to 4798 in just a day. He says its a good sign and told me to book a ultrasound for next week, he told me the ultrasound techs put not a viable pregnancy if there is no cardiac activity but I'm soo worried :(