Red, sore, inflamed gums

I was recently told I have mild to moderate gum issues by a dentist and I've been taking care of them, brushing twice a day in the morning and before bed as well as rinsing once a day and flossing at least once a day and my gums look and feel so much better. They're pink now and don't bleed when I brush, but are still receded and pocketed a little. I usually don't drink soda very often if at all. I just don't think it's good for my teeth and gums the way they are. But today I splurged a little at a friends house and drank some Root Beer. After I drank it two of my bottom teeth were sore and when I got home my gums on the front teeth (The ones that are most receeded) were red a sore.

Did the soda cause this and should I just stay away from soda all together?