Help: overheating super fast

I started T about two months ago and it's mostly going well. One thing I really struggle with is the heat though. My body seems to have completely forgotten how to regulate temperature. I used to be just fine with temperatures over 100°F, now it's around 90°F and I really struggle. I would consider myself rather fit, I swim 5 times a week, I go running and I work out with weights on a regular basis. But last week during a training session my head went so hot I had to take a break and cool down and the other day I helped a friend move houses and I got really scared my body would overheat.

I already upped my water intake, took my trainer's advice and watch my electrolytes after working out, hell, I even started drinking an odd mixture of cucumber, lemon juice, salt, pepper, parsley and sparkling water.

In general I think I'm treating my body well, I have a healthy and balanced diet, I'm also definitely eating enough protein.

I don't want to reduce physical activity, especially now that it's easier for me to build muscle and also not with stuff that used to be easily doable before T.

Any advice on how to help the body regulate temperature? Is this just a phase and will normalise again after being on T for longer? Or am I doomed to turn into a walking tomato every summer for the rest of my life?