This subchorionic hemorrhage is large comparatively. You have to take strict bed rest. Certain medication will be given by your gynac like pause, proleutondepo and other progesterone combination which you have to take strictly.
In case of bleeding you have to rush to hospital. There are always a chance of abortion or preterm delivery. Keep a watch by doing sonography regularly in this case.
Next Steps
strict bed rest
repeat sonography after one week
take medications