Retroactive FMLA Application

My wife missed work due to our 5-month old son's admittance to the emergency room with a diagnosis of pneumonia. She notified her employer that she would be out following normal call out procedures due to his admittance and required recovery time before returning to day care. During follow up with his primary care physician it was determined that our son need a longer recovery time due to complications from the pneumonia. She contacted her employer by telephone and then in person to request off for the rest of the week. The employer was then closed for a week due to a holiday at which time our son was then readmitted with pneumonia for a second time. My wife again at the open of business followed proper call out procedures, with a follow up call to her supervisor to check on the status of her request. Upon return to work she requested in writing retroactive FMLA use to cover her absence for the unforeseeable medical issues and complications our son had during a two and a half week period, one week of which was an employer scheduled holiday. She requested the leave specifically after her employer refused to pay her for the usual paid time off of the holiday week. At no point during her conversations with her supervisor did they mention FMLA as a possible option due to our son's illness and since requesting in writing for FMLA use two weeks ago, she has not yet received a response. We are wondering what step we should take next.