Sick after workout

I’m on a weight loss journey. I workout in the mornings before I go to work 3/4 times a week. I do fasted cardio (not eating before doing cardio) and usually I’m good. Today I got done and 20 min later felt so lightheaded, dizzy, and sick to my stomach. I had diarrhea and nausea. I ate an apple and had a protein shake to see if it was my blood sugar but it wasn’t. I’m very hydrated. Does anyone know what this could be?? I took preworkout too, but I always do that and never had any issues. What’s wrong with me ?? 😭