Internal bleeding

Went to the ER today for dizziness that almost caused me to faint. After a sonogram they determined that there was a yolk sac at appx 6 weeks but no baby present yet. There was also some bleeding noted at the upper and lower areas of the sac. I have not had any external bleeding or spotting at all and my HCG levels are increasing as they should. OBGYN said it's a little concerning but blood levels are good. Scheduled sonogram for next week hoping to see growth and/or heart beat. Any advice? Has anyone experienced something similar?