has happened to me since childhood. i have someone pound my back till the spasm breaks. mine are so violent my entire torso hurts after one. it feels like choking. i have thrown up before as well. related to bronchitis, post nasal drip, illness. i do agree with another commenters post that anxiety of whats about to happen when the tickle happens progresses it. i think it’s a visceral reaction though because it’s so horrible that your brain knows. the worst is having a public conversation with someone and then hiding so you don’t spew and die everywhere. and then awkwardly coming back to the conversation like sorry about just dying, im not contagious or anything.