Abdominal Mass

Hey everyone I need to know if someone has experienced this before. So I have felt this pulsating mass in my stomach for a few weeks now and it’s so weird. It’s mainly around my belly button and idk but it’s like I can move it around sometimes? And sometimes it just disappears. It just feels hard and kind of like a ball. I’ve been really gassy and cramping as well. I just feel off. Help!