If the rash has any redness to it, I would highly recommend you return for a strep culture. If the dots are small and red, it is called Petichii (sp?) the classic sign of the potentially serious strep infection.
If she is NOT showing signs of fever, restlessness, irritability and soothes quickly when annoyed, then the rash could just be a reaction to a dermatological insult. Then I would recommend bathing her in a nice, warm salt bath with colloidal oatmeal. Just dissolve a good cup of salts (epsom, kosher, sea, table, any kind) into her bath, stir in another cup of the colloidal oatmeal. Both elements will help heal and soothe her skin naturally without soap.
I hope she's back to normal soon.