M.K.
My son had a herniated belly button and it ballooned up and became larger over the first 3 months (it got to the size of a quarter). Yes, it would change size at times, including when he cried. I remember thinking "this is NEVER going to shrink down!" But it did start to shrink before 6 months and kept shrinking until it healed on its own. I think it was completely gone by 12 months or so. We were advised that most cases (not all) resolve themselves without surgical intervention. My son now has an "outie" but looks totally normal!