Do you have the baby monday thru friday straight? they don't pick him up after work and take him home to care for him?Wouldn't she see it starting earlier in the week, they don't just appear out of no where. sounds to me like she is just blaming you because it makes her feel better. I would just give it right back to her, when she brings him back request "cream" to be used at each changing (tons of it) and change his diaper every hour, go through them like wild fire. maybe even ask her if she'd like you to note the changings and she is welcome to count the diapers. I just give it right back if a parent doesn't respect my quality of care. MAYBE just maybe he has sensitive skin OR is he eating new foods? that can cause quite a rash sometimes. UUUGH! I really don't like difficult parents at all. good luck