Cramps

This is my secone pregnancy. I got pregnant in August and had a miscarriage early on. I found out recently that I am pregnant again (around 4 weeks) I have had mild to moderate crampiness off and on since I found out. It seems to be worse at night time. I had my blood work taken a few days ago and the doctor said my hcg levels are rising appropriately and my progesterone was really good. But I am still SO nervous because I had cramps with my last pregnancy. I have had no spotting or bleeding. But with the cramps off and on I am just scared its something bad. Did any of you ladys experience this early on in pregnancy?