I know that must have been such a Scare! Glad that everything turned out ok. Bella doesn't take the heat too well either. When we play outside for a long time, she's more than ready to come inside where it's cool. Also recently on a long trip, @rest stop I noticed she seemed to pant within only a few mins & went under the car for shade once, even after just drinking cool water. I guess some babies can take the heat better than others.
I would as everyone else suggested - talk it over with yr Vet. Hugs to you & yr baby!