Talk to Dermatologist on What Is This Skin Issue

My father age 57 well controlled diabetes hba1c 6 . He has this under his underarms he do walk 5km daily which cream should we use. Ye unky elbow kay opposite side py bhi tha after blood test syringe for a month it was not going away then used fucidin h cream it went away. Ye underarm may bhi nikal aya hai attaching pictures kindly tell me what is this and any cream?