Hello,
Triamcinolone is a highly potent steroid cream and this has planet of side effects. I advise you not to use it on the delicate and thin skin of the baby as it may cause serious side effects. Please get it evaluated from a dermatologist.
Till that time, make your child wear cotton nappies for some days instead of diapers and use hypoallergienic soaps and detergents which are non perfumed. Also air dry your child after each wash. Application of calamine lotion also helps. If the symptoms persist then please get an evaluation done from a dermatologist. I sincerely hope this information helps. Take care.