Seizure and delerium in thailand

Bassically i went on a trek with my brother thought a beach he was very hot / dehydrated. He started to feel faint and halucinate couldnt focus his eyes on anything, he then had a seizure that lasted under maybee 10 minutes maybee about 5 minutes maybee a bit less.
He stoped breathing i think and his eyes rolled back into his head. I foced his mouth open and tryed to breath in and pumped his heart, this made him splutter. and i noticed after a while he was breathing shallowly. he was coucious and didnt have a clue what was going on. I ran to get help and came back.

He had no idea where he was very red face and eyes and didnt want to drink delurium had no memory of the even or what was going on. we got him to have some water.

and took him to the beach stumbling it took maybee an hour and a half for an ambulance to get there and he coudlnt remeber what i said to him a few seconds before and didnt belive that it had happened. Massive headache Vomiting tons, red eyes teirdness lethargy. delusions / delurium.

we got him to the hospital he just watned to lie down was more competant remebred what i told him still being a bit delusional refusing to get drip didnt belive it was that bad red eyes extreme lethargy tierdness didnt want to drink. after drinking some water had biggest headache he had ever had.

after some time a few hours maybee 3 i convinved him to ge the drip for dehydration he was awre but unable to focus hold a conversation a fact he made note of himself very faint / weak he then went to sleep

firstly any ideas WHAT THE HELL HAPPENED
any lingering effect, brain damage/ effects from the seizure or dehydartion / heatstroke what could happen and is it unlikely if say your

in the hospital he had no fever but i think sunscream on his skin (so much) and sunburn elavated his temp in the forest a lot.

what do you think happened and do you think he will be ok, Made jokes towards getting the drip more concious but still very ill the drip seems to have helped

[garlgarrahha]

he may have had gastroenteritis as well