First, I'd think about finding a new vet. does the vet realize the severity of problem? If not, I'd take that picture in and show it to the staff and get that appointment moved up to now if you're set on the vet. Hopefully he/she knows bulldogs.
But aside from that, what has he been eating? Food place a significant role in bulldog health and allergies to his food can cause skin problems. I'm thinking drastic action is needed given the severity of the problem. Maybe putting him on a bland diet for starters and moving him to a high quality grain free food once he settles in a bit. there are forums here on Bulldog health and nutrition and I believe you can find the bland diet recipe there. If not someone more knowledgeable than I will spell it out for you.
There are shampoos and lotions that might help as well. They will be pointed out to you shortly by those who have dealt with similar problems. Good Luck. I think you'll find some help and lots of support here. Thanks for taking this guy in.
Looking at your post, I see that you are in Japan? You may have to mail order food in or make your own. There are recipes on this site too.
Here's the Nutrition & Food section http://www.englishbulldognews.com/fo...nutrition-194/
Here's the health section http://www.englishbulldognews.com/fo...og-health-175/