Miscarriage

Ca

Last week I found out I was pregnant and this past weekend I had a lot of bleeding and cramps, the blood was clotting so I went to the ER and they did the ultra sound and couldn’t find anything so they did a blood test and my levels came back as a 2, they are calling it a threaten miscarriage and sent me home that was on Sunday. Now I’ve stopped bleeding but I still have a lot of cramps and now my shoulder is starting to bother me, I’m not sure if it’s related or not but I’m just curious to see if anyone thinks this could be a ectopic pregnancy? With my levels so low and them not finding anything could it still be possible to have one?