Nipple Piercing Being Eaten

Well pretty self explanatory in the title. So ever since I got pregnant & gave birth to my daughter 8 months ago, my nipple ring (bar), one side of the ball looks like it’s being covered by my nipple slowly. I constantly have to push it so it doesn’t stay stuck & flat. It started on one & now both my nipple piercings are like that. I’ve tried washing them thoroughly again like when I first got them pierced but doesn’t seem to help much. I thought maybe I need a longer bar? Not really sure. Has anyone else had this problem or even know the name of it? I love my piercings & would hate to take them out so could use some advice on it. Thanks ladies!