I called my clinic today because of the lower left sided pain I was having and they wanted me to go to the ER. I went and they did an ultrasound and some labs and saw nothing no sac or anything in the ultrasound and my hcg levels were 490. So they told me that I am still very early even though I am supposed to be six weeks tomorrow. I go back to my doctor on Wednesday for another ultrasound and to check my levels but I am wondering can this happen or could I be a week or two behind?