Moveable lump in right lower abdomen. Possible hernia?

When I lay down, I have a lump in the right lower abdomen. If I press on it, it moves up into my abdomen. Once I stand up, it’ll be back in the lower abdomen. I went to my doctor and she ordered an ultrasound for next week. She never gave me any indication of what this might be. I’ve been stressed out so bad wondering if this coule be something serious. I’m 4 months postpartum, so I’m wondering if maybe it could be a hernia? Not sure if they move like that but I am bloated and having constipation along with it. Has anyone else had this? I’m driving myself crazy worrying 😭