3 weeks. Help

I found out Wednesday I was pregnant and went to the Dr Thursday and I've been having these Sharpe cramps in my stomach they did a blood test and found out I am about 3 weeks based on my hcg levels. Is it normal to have these Sharpe cramps every now and then? I also had an ultrasound done which I won't get the results back until tomorrow morning to make sure I'm not having an etopic pregnancy. I'm 22 and this is my first so I'm scared and any reassurance would be great.