if you sweating profusely with muscle cramp dizziness and either shallow or trouble breathing yes it is heat exhaustion. you should try to cool your body temperature by getting out of the sun look for shade or something cold to cool off and drink water to replenish what you just sweat out. if body temperature doesn't drop and continue sweat excessive amount you are going to go into state of shock by trouble moving and body can't sweat anymore when you need to cool down your body temperature
sweating profusely muscle cramps low blood pressure (80/75) and dizziness are these signs of heat exhaustion?