My Husband Suddenly Experirenced A Feeling Of Being Very Hot

My husband suddenly experirenced a feeling of being very hot in his head. His face had turned dark red. He felt dizzy and his vision was blurred. It subsided and he laid down. Stomach pain, constant pain not cramping. He is 62 years old in very good health, does cross fit 3 x a week. This morning had been working in the sun building raised beds, nothing terribly strenuous. Drank approx 8 oz of water while working outside for about 2-3 hours.