5 weeks ultrasound no baby?


I went to the ER last night. beucase I have some spotting and cramping. they did a vaginal ultrasound. The docotr told me. they seen a sack but couldnt see the baby.. (I also have an ovarian cyst on the left side. where i have the pain) so my question is has anyone else had an " empty sack and 5 weeks and 4 days. And everything turned out okay? they also did blood work and said my HCG levels did rise from last week. they also did a pelvic exam and said it all looked fine. thank you to any one who answers.