Toddler odd gagging behavior

My 3 year old son has always had a very sensitive gag.. he wasn’t doing it for awhile and I was happy we rid of it until my mom gave him pediasure and he threw up . Since then, he’s gagged and thrown up a little bit of food and milk every single day. It’s been over a week and we try not to pay attention to it but it’s eating me up inside and stressing me out . I scheduled a Dr appointment to have him checked on Thursday . Just wondering if this has happened to anyone else’s toddler ?