Illness

Bit of a long one. My son has been poorly for around 4 days now, he’s not himself all he wants to do is lay on me all day, he’s usually a very active toddler running around everywhere. He has diarrhoea, isn’t eating, and his temp is so high. Reached 39 degrees last night so I ended up taking him to A & E as I was so worried. the day before I took him to the GP and they told me it was a stomach bug. But last night at the hospital I was told they can’t pinpoint what it is and to just keep giving calpol and ibuprofen to keep his temp down? He’s just not seeming to get even a bit better each day, which is unusual and his temperature seems to spike high in the evenings, like really high which I was told as hospital there’s no explanation for ? I’m just worried it’s something else, but also my toddler is an absolute nightmare when they try and carry out checks on him it’s almost impossible as he’s kicking screaming crying and I have to restrain him which I can barely do and I don’t want to put him through that for the third time as it’s traumatic for him. What would everyone else do?