Heat exhaustion and dehydration advice

[Jazz48235]

My 8 year old son played in a football tournament yesterday for 6 hours.
Anyone in the UK will know it was the hottest day we've had this year and full sun all day without a cloud in the sky.
After we got home from the tournament he quickly became very unwell and ran a temperature of 39 and was shivering uncontrollably.
I was worried about heat stroke and dehydration so I called 111. They dispatched an ambulance.
Luckily we have a very good friend who is paramedic, he was off duty and came round straight away to assess my son.
He said as he was responding and all vitals were fine there was no need to go to A&E which reassured me so I rang 999 and cancelled the ambulance.
He has woken up this morning and is still running a high temp and feeling very weak and poorly. (Not moved from bed and it's 11am)
Anyway my questions are these:
Has anyone experienced anything like this before?
If so how long did it last?
Of course I am doing all the obvious like getting him to drink plenty and giving Calpol for his fever etc..
All the info I can get online is either heat exhaustion which should be better within half an hour or heat stroke which is potentially life threatening and nothing in between.
I'm currently waiting for a call back from an out of hours GP but just need advice in the meantime.
Thank you

It sounds much more likely to me that he’s happened to come down with some sort of infection (strep throat is doing the rounds again etc), than anything related to the heat per se if he’s got a proper good going high temperature like that.

Heat stroke would be very unlikely in yesterdays temperatures. Was he drinking during the tournament?

Sounds much more likely that he has a virus. Just carry on with calpol and fluids and rest.

Thank you guys.
I know the temperatures wasn't especially high but we are fairly confident it was the heat and a definite lack of fluids. He barely drank anything all day no matter how hard I tried to encourage it. They didn't spend any time in the shade for the entire day and no hats or anything
I got quite badly burnt even though I had sun cream on so the sun was very strong and of course we're not climatized to this kind of heat.
On the other hand, there could be more to it and there is potential for an infection as I'm guessing his temperature would have come down by now if it was only heat related. So maybe he had something rumbling and this is why he's been effected so badly.
I am STILL waiting for a call back from out of hours. Hopefully I can get him checked over, he seems to have perked up though.