I know how you feel. Saturday, I was shooting the rest of some 2 x 6 rafters on a 26' x 30' carport roof. Earlier in the week I had tossed up 20 sheets of 7/16 OSB and spread them out to have a safe walking area while working up high. I started fairly early, got the final 27 rafters shot in and was having early signs of heat exhaustion. I had already downed 4-20oz bottles of water and the sweat was just pouring off me. I took a break and caught my breath and made an attempt to cool down. I gave it 20 minutes, got up and measured and cut all my bridging material. I was going to get it nail on and had it all topside. That last trip up the ladder I felt the first dizzy spell. I decided to just pull the nailgun down, lock things up and call it a day. I was so beat from it, I left hand tools out, hoses, cords, levels, and anything else that was less then $50. I got the heck out of there and downed two more bottles of water on the 20 minute ride to the house.
That night, about 30 minutes after I went to bed, I had another 30 minute bout of muscle cramps. It was all I could do to try to stand up and walk them off as I was shaking uncontrollably. My muscles finally calmed down and gingerly laid back down.
I'm in my early 50's, but it's the first time that I've ever experienced the dizziness and cramps from the heat of the day. I reckon I ought to realize I shouldn't be trying to do things that once came with ease. I'll be pacing myself from here out.
Glad you were able to get cooled down!