(TW: talk of vomit) Stomach flu or rogue puke sesh?

My 6 year old was laying in his room with my husband. They’d fallen asleep together and I knew my 4 year old would be upset if no one slept with him so I decided to sleep with him in his bed. I woke up to my 6 year old scream crying and my husband frantically rushing him to the bathroom. He apparently threw up so, so much in his bed out of nowhere.

My husband said our son got up to get a drink of water. He came back to his room saying his legs hurt. My husband told him to get back in bed and he’d rub his legs for him. My 6 year old crawls in and proceeds to fully empty his stomach straight into his bed. My husband said it was like 45 consecutive seconds of barfing.

We got our son cleaned up and bathed and he didn’t end up throwing up again. He was laughing and joking with us once he was back in bed and happily sipping water. We tucked him in and he fell asleep content within minutes. It’s been an hour and a half and he’s still good.

Could this be the start of a bug or is it more likely a random expulsion? He did have a few salt and vinegar chips and some Greek yogurt for his snack before bed and I can’t imagine that combo is good on the gut but I feel like he’s had that before and been fine. Dinner was chicken noodle soup and he ate quite a bit of that as well. Drank just water throughout the evening.