Girls, has anyone encountered errors in the laboratory for determining…

Girls, has anyone encountered errors in the laboratory for determining hCG? I took it three times with a 2-3 day interval and got: 191, 490 and the last analysis was 40. It's been four days since the last analysis, there are no changes in my body, I went for an ultrasound first - the embryo is attached correctly. Waiting for the second ultrasound and a new hCG test and I'm really worried ?‍?️ I've already stressed myself out and gotten into trouble ?‍?️