Sounds like teething to me
We dont use Panadol/Neurophen here at all except over night if she is really bad.
Lots of comfort and you can try giving him a cold flannel to suck/chew on.
I find Charlotte gets really bad and loses the red cheeks the day she is actually CUTTING the tooth. So have a look in th emorning and you may find a tiny little toothie peg breaking through.

Also, if he is quite bad it could be because he is cross cutting - cutting more than one tooth at once. Charlotte has never had a single tooth, they always come up in pairs lol So I find is is particularly bad.

The teeth can tend to move up and down in their gums for a while too, and not actually cut through, so you may fin he could be "teething" for some time, months even. Charlotte showed classic signs of teething from about 3 months, but we didnt get a tooth until the top front 2 vcame through at 9.5 months.

Hang in there - lots of cuddles and hopefully he will learn to deal with some pain, if he is not sleeping well, try some Brauers teething relief.

HTH