I have a trapped gas in my digestive system

What do I do? It hurts so bad!
Like it's in my lower belly and than I feel the gas in my throat and I end burping but just now when I burped some acid of the drink I had came up alittle. 
Is this normal!? I'm only 18 weeks pregnant. I haven't been able to use the bathroom as well in like 2 days or so.
I hate the pain of the gas, it's literally like a gas in my chest.