Suggest Treatment For Acne And Excessive Dryness Of Skin

hello..good morning...i have a problem of acne and i hve been on sotret for like 20 days now...its causing excessive dryness of my skin on my face and i also have excessive dry skin on my arms and legs now..and it pulls a lot wen i move ..i went to the dermatologist and he asked tht i continue sotret but only alernate days and asked to hve multivitamins as well..he gave me Benxop facewash for dry skin on my face and he gave me Aldry lotion for dry skin on my arms and legs to apply at nite..but wen i applied it...it actually caused even more dryness of my skin and my skin became white and scaly ..what should i do? i called my dermatologist to ask him about this and he told me tht it is a side-effect of aldry and tht i shud stop it for a few days and then continue again..but i dont understand why shud i use aldry for dry skin wen it is used for treating hyperhidrosis...!!! Could you please help...thanx