I am fasting right now, day 9 completed, I started with two days of Water Fast and then dry fast. I had to drink on the 5th day of my fast, one, because of extreme dryness in my throat and tongue. So just be carefully and drink water when your body demands. People have dry fasted for upto 14 days. Someone on this forum have gone upto 9 days. You are lucky, your doctor understands and supports fasting. My doctor does not eventhough he is practicing natural medicine.
Dry fast will help you with the flu. One feels weak whenthe body has toxins to get rid of.
Do you have a tongue scraper? I use one regularly to clean my tongue because I do not like how my tongue feels and also I don't want the gunk going down in my stomach when I drink water.
Keep up the good work. Make sure you do not eat mucus producing foods and your food is plant based after you break your fast to continue healing.