Is Brown Bleeding At 16 Weeks Of Pregnancy A Cause For Concern, Given My History Of Threatened Abortion And A Twin Pregnancy With One Empty Sac?

Hello, I have had threatened abortion when I was 8weeks and 6days pregnant and it was quenched. Then I went for a scan after two weeks and found out that there was two sacs, one habours active fetus and one was empty. But now I am 16weeks pregnant and I started having brown bleeding again. I don t know what to do, just confused