Nipple shield cause gas??

My baby has been crying excessively and it isn't at certain times of the day...

We thought acid reflux so we have been giving her medicine for the past 3 days. We do think she has it but she still sounds upset so I'm thinking maybe it's gas....

My nipple shield doesn't have good suction and milk will leak on the bottom of it meaning there is air getting into it and she makes noises while she sucks. No lip or tounge tie so it's not that. I'm trying to rule things out. Could this be causing tummy aches from gas??