It could be the baby stretching his legs and pressing on your ribs, or it could be a lot of other things. Kidney infection, appendix, you name it. Please ask your doctor, there are just too many possibilities.
I will be 29 Weeks on Thursday, the pain is more towards my back then stomach
You are pregnant? Sometimes round-ligament pain feels like that. Ask your doctor at your next visit, or if you think it is more acute, call now and ask to be seen.