Could well be the virus!
It tends to follow a similar pattern, but doesn't have the same affect on my BG every month. Some months I don't notice much difference, others I'm like... woah!! 😱
I can't comment on the menopause aspect, but I definitely find my menstrual cycles affect my BG. I tend to run high for a few days before, then slightly lower than normal the first couple of days. It's great fun!