I Am 30weeks6days Gestation. At The Start Of The Week

I am 30weeks6days gestation. At the start of the week I was rushed to hospital with loss of blood dripping down my legs and upper abdominal pain with what felt like many Brixton hicks contractions. After doing tests and ultrasounds they don't know what's caused the bleeding but my baby is measuring 2 weeks behind. I have now been referred to see a specialist and repeat scan for growth as well as being put on bed rest. What could this mean? I am a first time mother and have had a good pregnancy so far.