Hello, My Son,who Is 10 Yearsold , Has A Rash

Hello, my son,who is 10 yearsold , has a rash that is only on the trunk of his body (back and chest). He tells me that it itches. The rssh looks like dry skin and it has little scabs ( I think maybe caused by his scratching). I have been applying Triamcinolne Acetonide Ointment which was prescribed by the dermatologist for a previous condition when he lost a patch of hair a last year. Do you think this is acne? Could I be making the condition worse with the Ointment. Thanks