I had the sleeve performed four days ago. When I drink or eat, instead of having a sense of fullness, I get a pain in the middle area of my chest. It feels like a huge gas bubble. So the feeling is more like pain rather than nausea. Has anyone experienced this?

I did. For me I think it was still the gas they pump you with. It subsided after a few days and with moving around more.

Yup. It may be the gas from surgery or you may be swallowing too quickly or too much.

Yes for me I was gulping not sipping....

That sounds like pain from eating/drinking too much at one time.