To properly assess the MDM of this visit, I would need to see the whole patient chart. The MDM could be Moderate if the Medical necessity is there. However, if it's just "vanilla" OM and HFM disease, then slapping an Abx and call it good, might not agree with a Moderate MDM. What is in the History? What about the Exam? Is there anything that the patient's condition might be severe enough to warrant a Moderate Risk? I used to work for a provider group who was determined to bill 99214 for most QuickCare/ExpressCare (visits manned by PAs/NPs) just because they included an Rx script. That clinic completely missed the boat on Medical Necessity and they will discover that come RAC audit time.
I think we often tend to get a little pigeon holed when using a quantifiable tool like the Marshfield Clinic tool, because this tool makes auditing the MDM so much easier, that we forget the real trump card; Medical Necessity. Because Medical Necessity is so qualitative and hard to pin down without a fair amount of clinical background, you should probably need to see the whole picture of the patient's conditions, instead of just looking at sections of the chart. Depending on the chart note, I could honestly see this go either way, however I am leaning towards 99213 unless there is something that would convince me that the OM and HFM disease are severe enough to be Moderate.
As a minor detail, if you do follow the Marshfield Clinic Tool, then you cannot assign 6 points for 2 New Problems to the provider w/o additional work-up, as this maxes out at 1 problem. This would instead result in 3 points, which would not sway the overall MDM in either direction, but something to consider.