Do TVS,it could be SCAR PREGNANCY, see for GS.

Relax for the time being. The placenta shifts as the pregnancy advances. So nothing may happen. If you have slight bleeding or blood stained discharge then action will be taken as per the circumstances.

You might have bleeding because of this placenta so you need to avoid intercourse, heavy work, weight lifting and report to your doctor whenever you have bleeding or spotting. Usually low lying placenta migrates upwards with the progression of pregnancy, but placenta covering internal OS usually doesn't migrate and you might need cesarean section for the delivery.

This condition may cause bleeding. You have to  avoid lifting heavy objects. No intercourse. The placenta will gradually  move upward  as the pregnancy advances.