Hello,
I hope you're not in too much pain.
Usually lesions occur at the angles of mouth opening because if the nutrient deficiency like iron and
vitamin B12 and also may occur due to viral infections. But infections associate with high grade fever and chills.
If its not happening gateway then it might be because of iron and vitamin B12 def.
Kindly have 2 eggs per day, leafy vegetables as a pert of diet daily so that you can get enough of the nutrients but before that you need need to see a general physician in order to know the exact cause of your problem as I have discussed possibilities only.
Thank you.