Does he have an ulcer or anything? It sounds at first like some sort of acid issue. It sounds like he ate something that disagreed w/ him, I've never heard anyone w/ an sv say their stomach burned?
Anyhow, you weren't near him when it happened and just being in the car w/ him and him coughing before hand isn't going to contaminate you. Keep doing what you're doing (BLEACH, hand washing) to be safe side in case it is an sv but really doesn't sound like one to me.
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