Hi Alpha, I know you said you take your bulldog to a french vet, did they give you any ointment for the yeast?
You can try using over the counter yeast ointment (for the ladies), just make sure you don't put it in an area where your bulldog can lick it.
Also, you mentioned in another post that you give your bulldog a wet down to cool off. Trapped water or too much water will cause yeast. Make sure you dry him off well, especially in the wrinkles after his cool off.
Where is all of the yeast infection at? In his ears, in his nose rope, tear stain area, under the chin, paws?
There is anti-yeast ointment you can get from the vet here in the USA. Can you call your vet and ask if they have some?