Does A Decrease In HCG Levels Indicate A Miscarriage During A Pregnancy?

Hi, i am a 29 year old woman whom is currently 4 weeks pregnant. I have experienced pain and cramps on and off in the last week and had a vaginal ultrasound which proved how far along i was as well as there is a sac. It was too early too tell last week if the sac was developing or not. The cramps have settled down quite a bit and there has been no signs of bleeding up till now.
today is thursday, on monday i had a blood test to check the level of hormones and their was 33,350 on wednesday (yesterday) I had another blood test and it has decreased to 33,050 i'm due to have another one tomorrow and I no nothing is completly certain till then, but in your opinion is a slight decrease in hormone level so early on always mean a miscarriage? Is it possible that baby will be ok? Have you ever heard of this before and the pregnancy carrying to full term?
Thankyou Emily