Spitting up?

Geneva • 23. Married. SAH boy mom to Asher & Jensen💙
My son is 3weeks. He's been spitting up a lot lately. Sometimes and hour or two after feeding! What could this be from? I burp him after each breast and keep him upright ten to fifteen minutes afterwards, sometimes more but it doesn't seem to help much. I'm exclusively breastfeeding him. Could it be my diet??