Im so worried..

So this is my 1st pregnancy and im 4 weeks and 6 days. I feel alot of air and but stomach keeps fluctuating. Like itll be puffy and sometimes completely flat/normal. Is that normal? And my boobs used to hurt alot last week, but now not as much. Kind of worried about the cramy feeling (even though itll go away after 10 seconds)....just need advice and to know when i should worry...