DOGS EAR IS LARGE AND IT SMELLS?

ok so i have a french mastiff he is a good boy but he smells he must have some type of skin condition idk but what also is bad is the fact that his ear is like 2 times the size of the one to the right of it. the ear also gets some type of discharge. idk what this is it is very gross. he has had this probmelem for about a year now and we dont no what to do the docterstold us it was a yeast infection but we dont know. it is smelling up the house its gettiong to the point to were the cloths you were are smelling lke it. how the heck can i cure this?