Help! Important! Is my upset/acidic stomach linked to drinking soda?

I drink large amounts of soda (Dr. Pepper) I'd say between 1 and 5 cans daily. I've been doing it for a very long time, and I hardly drink water. All of a sudden, I've felt sick to my stomach for a few days now. Sometimes I feel like I'm going to throw up, other times I feel acid rising in the back of my throat...