Unexplained high BG readings

I am Type 2 with normally very good BG levels year in year out. Yesterday and today I awoke with blurred vision which caused me to check levels both fasting and pre and post prandial. Fasting as high as 8.0 with maximums between 10-12.5+ during the day and now before evening meal 8.0 which is five and a half hours since lunch. I have not changed my lifestyle one iota and drugs regimen is unchanged. I do not have a fever or any other signs of illness with the exception of a frontal lobe headache which, after two days, I had to take Paracetamol reluctantly (being on Warfarin) to clear it successfully. Any ideas folks please?