Firstly, It can be due to vit B deficiency. Take some vitamin B complex for some days and see if your symptoms improve.
Secondly, it can be due to atopic dermatitis or eczema("Atopic" refers to a group of diseases where the
re is often an inherited tendency to develop othe
r allergic conditions, such as asthma and hay fever). Cheilitis(Inflammation of the
skin on and around the
lips)is often seen in atopic dermatitis.Diagnosed by blood test like RAST.