Suggest Treatment For A Sore On The Corner Of Mouth

I have had a sore on the left corner of my mouth for about a month now and it wont go away. I've used blistex, neosporin, rubbing alcohol, peroxide, anti-fungal cream (which looked likeit made it worse), abreeva, and hydrocortizone cream and none seemed to work. I've also upped my vitamin b intake too. how do i get rid of this sore?