Thank for asking to HCM, dehydration
is out of question dehydration means you are loosing you body fluid either due to vomiting or watery diarrhea
these is medical condition apart from this excessive heat can also cause rapid dehydration, you do not have such condition, it maybe some kind of muscular pain
have some analgesic
,,, do some exercise, will relieve the problem ,,, Have a good day.