Is it possible that you are starting a cold, flu, tummy bug, or have developed another sort of infection?
Or are you stressed or sleep deprived?
All of those things can raise my blood glucose quite significantly, and keep it raised until the problem goes away.
I should keep monitoring it closely.
How long does it take to get an appointment at your surgery? It may be worth making one in advance, before your doctor gets back. You can always cancel it if you don't need it.