Don't know this is ok

I woke up this morning and I think I got up too fast but I got thee worst pain in my lower right side, it literally took my breath away! I'm only 4 weeks and 5 days and yesterday I was at the doctors and they saw a sac but no yolk yet (she called it an empty apartment). I'm not bleeding or anything but now my lower belly is sore. Definitely hurt me big time! Since finding out I was pregnant I've had a lot of heavy cramps, and pain on my right side. No spotting or anything. Can someone help me? Is this ok? I go in next week for a second scan to see if they see the baby. I feel very worried.