I'm 5 weeks and I've been having a bit of pain. Went to the emergency room and they said I might be…

I'm 5 weeks and I've been having a bit of pain. Went to the emergency room and they said I might be miscarring but no bleeding and I have a cyst right by the baby... Has anyone else had this problem and how do they know for sure its not another baby?... HELP PLEASE!