Temp keeps going up and down over 2 days. Docs?

[crystalgall]

DS (4.5) has had a temp for 2 days.
It keeps fluctuating between 37.5-39.1 (the latter temp was only once).
We've been giving calpol and nurofen and it lowers for a bit and then rises again.
I haven't really been keeping tabs on when I'm taking the temp so not sure what's going on.
I know the advice is to wait 3 days before taking them to see someone so should I just wait it out?

He's not eating much (bit of weetabix and toast over two days) but is drinking water through the day. Is sleepy and a bit listless but can be cheery and chatty at times. Hasn't played with his toys at all for two days so definitely not his usual self.

I'm
Just a bit concerned at how it keeps fluctuating. It hasn't dropped below 37 since Saturday night.