After 3 Weeks Of Strenuous Training In The Heat With

After 3 weeks of strenuous training in the heat with very modest food intake, my son over ate "pigged out". He then vomited and developed a headache behind his sinuses and eyes. I know the vomiting is probably a reaction to the overeating, but could the headache also be a reaction as well? During his training he was drinking electrolytes and water, the day he over ate he had a Gatorade and then water for the rest of he day. Do I need to worry?