What made my pancakes taste fizzy?
I am willing to bet the high acidity of the berries reacted with the baking powder component of the pancakes.

Pancakes are just barely cooked batter and the carbonates are still pretty active, which is what makes good swiftly fried pancakes fluffy while pancakes cooked on too low a heat become rubbery and floppy.

It's also why if you replace fresh milk with fresh butter milk  (not buttermilk pancake mixes), it makes fabulous fluffy and tastier pancakes.

I am willing to bet your pancakes are pretty darn good aren't they?