I have acid reflux every day. it didn't used to be as frequent. i'm taking vitamins & wonder if they might be interacting adversely with each other.

Possible: There really isn't any way to say for sure about this except to do a little trial & error on your own. The main goal is to not change too much at once. Stop just one of your vitamins for several days, probably a week, & see how you feel. If no different, add that one back & stop another one for a similar length of time. This way you can tease out what the offending substance might be. Good wishes