Brain fog after exercise

Patient: I get severe brain fog after weight training, what could be the cause?I am A personal trainer and my diet is on point with pre and post workouts, i am doing hypertrophy so shouldnt be stressing the cns as much as strength training should. i take a multi vitamin, vit c, fish oils in the morning, should i take another multi after the workout?

Symptoms: brain fog, cant concentrate, mentally drained and tired