My body overheats when it is hot outside?

.. Even when its 70.i can overheat. I dont sweat anymore. Is my body lacking something like a vitamin or a mineral or anything?? I used to be able to be outside in 100 deg weather and everything would be fine. Now it gets 70 out and i panic cause i dont want to get sick...My body overheats when it is hot outside?
Drink more water
Are you taking any medications? How old are you?
A kid at my school had something similar to this. I always saw him drinking water all the time and he said he took vitamins every day.
Avoid all spicy food and head for places that are cool when it gets warm.
H2O............you sound dehydrated.