Baby rash from Baby detergent

#pleasehelp #firstmom hi everyone, my baby develop some kind of rash and was inform by doctor that it is a viral rash that will go off on its own about 1-2weeks. However, it’s been more than a week and we suspect could be from a baby detergent. Anyone has had this issue before? Any advice on what baby detergent is good? Would really Appreciate for your help.