Fever and hallucinations

My DS4 is nearly four years old and has been unwell tonight. He went straight to sleep at 7 and looked glassy eyed so I took his temp and he was 37.5. An hour later I checked him again and he was still warm but sleeping.

Around 9 we heard laughing coming from his room and went down to find him giggling and saying 'that's funny' over and over. He was starring blankly at his wall and was drooling too. We couldn't get him stones nap out if it for a while. I lifted him up and felt the heat radiating off him and thermometer said 39 degrees.

I carried him out to the kitchen and it wasn't till probably 5 or 6 minutes that he fully came back and was able to answer question.

About another half hour later we were finally able to convince him to take some panadol and then put him back to bed and within five minute he vomited.

I keep checking him and he seems ok. Temp around 37.5 but sleeping soundly. I wouldn't have thought his fever was high enough to cause delirium or hallucinations. Assuming he's ok in the morning would you take him to get checked out or not worry? Anyone else experienced anything like this?

I haven't had it with dd, but my dh is very very prone to fevers and if he lets it get around 39-40 he does sometimes hallucinate. Once the fever drops it goes away straight away though. Dd gets fevers at the drop of a hat too so I'm waiting for when she starts too but we dont usually let her fever get over 38.5 as after that it just shoots up so fast.
Whenever dd has a fever, we only have her in a singlet, if that, mostly just a nappy, make sure she has panadol and I check on her every few hours during the night if shes not with us.
Often when she's got a fever she sleeps with us though as I'm paranoid her fever will get too high and she'll convulse.
Maybe keep an eye on him and if he's still very out of it in the morning and isnt too warm get him checked out by the gp? Otherwise, if he's normal I personally wouldn't worry. Odds are he could've been still half asleep.
Hopefully the fever will break soon hun!! :(