Pregnancy symptoms are similar to heat exhaustion. Heat exhaustion can be alleviated by a cool room, hydration and rest. How frequent are pregnancy symptoms and if the solution to helping someone recover from a heat exhaustion doesn't help an individual suffering from an assumed heat exhaustion, is it safe to say that the person is pregnant. Ofcourse putting aside the more straightforward pregnancy blood test and etc…
Not pregnant just playing doctor. 
Well your right in that sense yes but Heat Exhaustion is also due to excessive loss of water and salts.