Brief Answer:
Probably hormone imbalance, further examinations are needed.

Detailed Answer:
Hello dear and welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice.

As per your query, I explain you in detail.

I am glad that your biopsy is negative. This examination excludes the abnormal growth of any cells in the uterine tissue.

I also see through your query that internal and external ultrasound is normal.

These examinations exclude possible causes of bleeding such as fibroids, polyps or cysts.

At this point I would think that a possible cause can be a hormonal imbalance.

I suggest you to do an estrogen and progesterone blood level.

I also suggest a thyroid hormone level .

Other possible causes of abnormal bleeding can be stress, infection, or abrupt weight change.

Meanwhile, I suggest you to stay calm, eat healthy and take vitamin K supplements to prevent further bleeding.

Hope I have answered your query. Let me know if I can assist you further

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