Today with my 3.5 yo we were out with friends at a children's museum, had a picnic lunch, played at the playground and everything seemed fine. On the way back, my son said he needed to poo, so I took him to the toilet and nothing happened. Then, on the metro ride back he started to say he felt sick, then he started to cry, which I knew meant we needed to act fast. Luckily the train had just stopped and I rushed him off as he started puking. After cleaning what we could, we got back on the train and 2 stops later, he said he was going to be sick again so we again got off and found a trash can just in time. After that he seemed a bit shaken but fine. We walked the rest of the way home and after cleaning him up, he went to bed (at 5pm) and is still sleeping. I have no idea what could have caused it since he had been completely fine until the incident. Has your LO ever been sick for no obvious reason?