help.

Okay guys so I've been on here recently talking about how I was told I was having a miscarriage, well now (two and a half weeks later) my hcg is going back up. My doctor is telling me that it could be a viable pregnancy, abnormal pregnancy, or a TUMOR! I just don't know how it could be a viable pregnancy when my levels haven't gotten above 449 since being told I was miscarrying. Can someone shed some light please? Has anyone else had this happen?? I'm freaking out, because if it is a tumor, why is he telling me it's just a waiting game until we can see something on an u/s? Shouldn't he be really concerned if it is?? 😭😩😔😒