smart under (something)
1. To experience sharp, stinging, typically superficial pain caused by something causing injury or harm from above. The child's hands smarted under the crack of his teacher's ruler. As my head and face began to smart under the searing Arizona sun, I cursed myself for forgetting my wide-brimmed hat.
2. To experience an acutely oppressive or burdensome source of mental or emotional distress. The film should resonate with anyone who has ever spent their days smarting under the weight of a soul-crushing, uncaring job. I smarted under the furious glare of my teacher as I crept into class late and slinked over to my desk.