Threatened Abortion

Hello, I’m 6 weeks pregnant in my first baby and today was so overwhelming I would love to hear some reassurance:

While at work, I noticed brownish discharge that I saw for first time since pregnancy so I called Obgyn clinic and told me to rush to ER. At the ER, they told me it’s all good and baby’s heart is beating but prescribed me Dydrogesterone. Is this normal? If all is good, do they usually prescribe Dydrogesterone?