What Causes Soreness Around Lower Legs,scalp And Around Face?

my mother is 98 and has for the past few years crusty sores on her lower legs, scalp, forhead and side of her face. they very rarely are open but look more like hard thick scabs that never go away. they start off as a red sore that is not really sore. sometimes they itch. we have tried different things but nothing helps. can you tell me what they are and if you recommend any treatment or special diet? they do not cause too much discomfort they are just a nuisance and unsightly. thanks.