My son is three years old and last night when he was sleeping I noticed he had a lump (like a small ball) at the top of his stomach between where his ribs meet. I placed my hand over it and it moved to the left and/or to the right, but would come back to the middle when I released my hand. It was not hard lump but you could see it through the skin. I looked this morning and could not see anything (but it was hard to get him to lay still enough for me to see) and I asked him if his stomach hurt and he said no.