I'm a streetworker, and during the day, when it gets hot, I start getting light-headed as I work. When I drink down some cold water, it seems to make the light-headedness worse. After the day is over with and I go home, the faintness goes away, but is followed by a severe headache and tiredness. It leaves me to tired to box or anything. Is this a sign of a near heatstroke? (Not an actual one, but coming close to having one)?