Hcg levels crazy!!!!!

So two weeks ago my levels were at 3,900 that was April 12 now yesterday April 27 there only at 4,700?? Doctor said most likely am going to lose the baby am 6 weeks and 2 days now he sent me to retest my levels same day yesterday to see if it was a mistake of the lab or if they are lowering then they came out to be 5,200 ?? Am so confused what could it be I was having some mild cramping no bleeding they are Watch for etopic to be on the safe side but they don’t see anything either

Another note on Thursday I had an ultrasound were we saw the baby and a heart beat and yesterday when they did another ultrasound sound they said they saw nothing not baby nothing just a sac all the doctors didn’t understand it they called the tech who did find the heart beat to make sure that’s what she saw and she says she stands by it we have pictures am so out of it I don’t know what to do am reading stories to keep faith others that not get my hopes up anymore this breaks my heart because we been ttc for 5 years now anyone ever gone threw this or had any advice ??!?!? Sorry ladies just really need some support and words of encouragement !!!

Thank you all