Giant gas bubble?

I'm a FTM, 26 weeks 2 days prego and am wondering if other moms have gone through this or are going through this...I'm thinking its normal growing pains.  Baby is moving tons, however I feel like my stomach is one giant gas bubble that I cannot relieve with a burp. It's making it difficult to breathe in certain positions. Baby is head down and is using my organs as a trampoline, or so it feels that way. Is this what a growth spurt of the baby and uterus feels like? Anyone else experience this?