That could definitely be your little baby!! I'm 26 weeks and within the past 2 weeks I have been feeling a hard knot right under my rib and than every once in a while I can feel him kicking! Man it hurts so much!! But if you look at my tummy he is sitting so high that he is prolly in my ribs, lol. But I bet it is your baby...just wait until they get bigger...can you imagine!?? But its all worth it :)
You bet that little "stinker pinker" (a loving term I assure you) is probably kicking your ribs. She has more room now than she will in the coming weeks and is probably a "leg stretcher," like one of mine was. Even my bobbies were kicked when I bent over.
The fundal height of the uterus is higher than you think at 24 weeks. At 16-18 weeks the uterus is at the height of our belly buttons, so you can imagine that your sweetheart, is higher than that now.
Enjoy that kicking mommie. If she stretches out that leg and just won't relax it, rub her little foot and she if she will find some place else to kick her precious mommie.
She just might be a long baby, also. With long legs. You will know soon enough, when you hold that precious one in your arms. Don't forget to write this "rib exerpience" down in your baby book, so you can remember the joys of every part of your pregnancy.
God Bless you and your little one,
Heather