The most common cause of angular cheilitis is vitamin deficiency and most specifically vitamin B2. There can be other causes also like fungal infection or viral infection etc. Although proper clinical checkup would be the most appropriate step but you can continue multivitamins for these symptoms and if they don't subside in 6 to 7 days you should consult a dentist for the same. Ointments which are to be applied inside the mouth (like dologel CT or hexigel)do not have effect on the outer skin of the lips or the face, so the most appropriate thing would be to apply simple moisturizers or cold creams so that dry skin in that area remains supple and causes least irritation. Regards

Hexigel/ dologel can be applied. Since your daughter is only 5 , you can apply glycerin for her. Add a vitamin bcomplex tablet to your diet and a bcomplex syrup ( like nutrolin B. Syrup) for her.