Talk to Gynecologist on Vaginal Bleeding

I had my last periods on 22 September which were already 2 days late , and I had blooding only for 3 days and then stopped. Then afterwards on 30 of September only small drop of blood came from vagina and then on 9 of October I had severe abdominal cramps along with diarrhea, I took Imodium 3 times and then I started bleeding from vagina with lots of blood tissues and my blood was dark brown . And after 2 days this blood stoped .

Doctor suggested me for pelvis ultrasound and beta HCG test which is normal.

What should I do now? Plz suggest me