Cramping

I'm 6 weeks pregnant and since I found out I was pregnant (3 weeks ago) I've been constantly getting this sharp like period cramping pain. My OBGYN keeps saying it's normal and I've annoyed him enough to do 3 different hcg blood tests to make sure my numbers keep going up (which luckily they are and last week they were already in the 5,000 range). Is anyone else experiencing this pain?