Please help !!

lori

My 9 months old baby having this problems !! I took him to doctor dr just said it’s just infection so she gave him acetaminophen and cephalexin and hydrocortisone cream but seems like rash is going all over his body now even his fingers N private area. I’m just hate to see him like this! Does anyone know anything about this symptom !! I’m so worried about my baby he is so miserable . Any advice I would be appropriate!! Thank you !!