Eating and air pockets in the gastric tube?

I'm still trying to figure out my new normal. I'm 8 weeks out from my surgery and 2 weeks of eating soft foods moving into expanding what I am eating. I've started eating a sandwich on toasted bread for lunch.

I've noticed the last couple days when i was eating that sandwich I start feeling pressure in the upper chest like the lungs are congested, then I start coughing. Eventually
I get kind of a burp or an upwelling of air from the lower end of my "stomach" ( or do I know refer to it as a gastric tube?). Then the pressure seems to go away.. Is that pressure normal and will it diminish over time?

I'm also trying to figure out how soon I will be able to start eating other items like fresh veggies, lettuce peanut butter. I plan on asking the surgeon Monday but I was just curious.

The transition to solid food took a little longer because the remainder of the stomach was in tough shape after chemo and radiation treatments and I developed a fistula in the neck, but I'm getting there.