Lightheaded. Nausea.

Hey everyone. Today I woke up and went to work (I'm a nanny) and I felt great. Ate breakfast. Drank water. Went to the bathroom. Took the older child to school and was tidying up some clothes around 9am when I started feeling like I was gonna pass out. It honestly feels like I'm kind of high (which I'm not) but that's the feeling. The lightheaded and delayed reaction. I'm not stressed. I love my kids and had a good morning. I slept well. I ate and drank and showered. What's wrong with me?