Suggest Treatment For Cracks On Skin All Over The Back And Stomach

my son is diagonised prolifrative glomeruli nephrititis and advised to take 120mg of wysolone alternate day for one month.after one month tohave induction treatment .but due to some problem i failed to consult the doctor after one month. now my son is still taking 120 mg wysolne on alternate day.He has developed long line of cracking skin marks all over hisback and stomach and on his arm also.
kindly advise me what i should do for him.
height-6ft 2in.,wt.72kg age-21yrs.
medicine using-
wysolone120mg alternate day
listril5mg od
starvas 20mg daily
pantocid 40mg daily b/f