Your chances of becoming a heat casualty as a survivor are great, due to injury, stress, and lack of critical items of equipment. Following are the major types of heat casualties and their treatment when little water and no medical help are available.
The loss of salt due to excessive sweating causes heat cramps. Symptoms are moderate to severe muscle cramps in legs, arms, or abdomen. These symptoms may start as a mild muscular discomfort. You should now stop all activity, get in the shade, and drink water. If you fail to recognize the early symptoms and continue your physical activity, you will have severe muscle cramps and pain. Treat as for heat exhaustion, below.
A large loss of body water and salt causes heat exhaustion. Symptoms are headache, mental confusion, irritability, excessive sweating, weakness, dizziness, cramps, and pale, moist, cold (clammy) skin. Immediately get the patient under shade. Make him or her lie on a stretcher or similar item about 45 centimeters off the ground. Loosen his clothing. Sprinkle him or her with water and fan him or her. Have him or her drink small amounts of water every 3 minutes. Ensure he stays quiet and rests.
A severe heat injury caused by extreme loss of water and salt and the body's inability to cool itself. The patient may die if not cooled immediately. Symptoms are the lack of sweat, hot and dry skin, headache, dizziness, fast pulse, nausea and vomiting, and mental confusion leading to unconsciousness. Immediately get the person to shade. Lay him or her on a stretcher or similar item about 45 centimeters off the ground. Loosen his clothing. Pour water on him or her (it does not matter if the water is polluted or brackish) and fan him or her. Massage his arms, legs, and body. If he regains consciousness, let him or her drink small amounts of water every 3 minutes.
Source and material above found in the U.S. Army Field Survival Manual 21-76
(Please do not attemp without proper reseach or training)