Update! After a horror Saturday night I took DS2 to an "after hours" GP as my GP practice was booked out. She had a cursory look over him and said she didn't think it was tonsillitis, probably a cold and teething and to stop the antibiotics as they were pointless and he didn't look too sick!!! She didn't bother taking his temp.
When we finally got home DS2 had droopy red eyes, was unusually quiet and refused his lunch. He had a sleep and woke screaming with temps over 40!!! I took him to the hospital where they said they could see his infected tonsils and recommended a change of ABs. They took a wee sample which was all clear. The hospital staff were awesome, reassuring and supportive of my mummy instincts as opposed to the dismissive GP

So we've had two lots of the new ABs, his temp before the next lot of meds is still in the high 38s my poor little man... I think he'll need at least another day at home but my classes are running riot at work so DH will stay home tomorrow and I'm home Wed/Thursday anyway! It's been more than 84 hours of fever and I've had enough!!!