Exercising and temperature raises early pregnancy

I'm terrified that I overheated this past weekend, we went for a 5km walk at about 8am on Sat, it wasnt too hot outside (I live in South Africa - and was about 26 celsius/ 78,8 fahrenheit) but towards the end I felt very flushed and hot in the sun. Now I'm worrying - my husband reckons I was fine as my skin wasnt burning up and I was keeping hydrated.

I'm seeing the dr soon so I will ask him about it - but the anxiety is real! :/ Had a mc in August last year with our first and just terrified of every small thing this time round.

Does anyone else feel flushed when exercising?

I'm about 5/6 weeks pregnant - not 100% sure as I have PCOS and ovulated way later this cycle than expected but all my blood work so far has come back 100% and on track.