The looming threat the party assumes is behind any sudden pain Carl feels, and briefly blamed for his chest jolt.
When Imani casts the borrowed Tripper spell inside the naga castle, Carl feels a searing pain in his chest and yelps like he's been shocked. Everyone around him immediately looks over, worried — they were worried about the Bedlam Bride.
Carl shakes his head. It was only the notification from Imani using his spell, and it kinda hurt. The moment shows how completely the Bedlam Bride now occupies the party's threat model: any unexplained pain in Carl is presumed to be her.
It is the ambient dread that colors every unexplained symptom Carl shows.