Hi, My Two Year Old Is Just Getting Over The

Hi,
my two year old is just getting over the flu, he's much better now, and his playful self. I've. Just noticed however, that his bellybutton is now looks like an outtie when it has always been an innie. I'm not sure either this would relate to his recent flu or maybe he's had to much to drink or eat? Should I be worried? Are there symptoms I should be watching for? Or am I over worried. Please advise. Thank you.