C.O.
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HFM disease shouldn't take 3 months to go away...10 days..it's a virus so no antibiotic will work for it.
Sounds like he is over medicated with antibiotics ESPECIALLY for a virus...antibiotics do NOT work on viruses ONLY bacteria.
If he's eating - then he probably doesn't have HFM as the blisters can get really bad in the mouth and throat.
Get a second opinion. Dump this pediatrician as it's obvious he doesn't know what he's doing...(prescribing antibiotics for HFM and THREE creams for the blisters..)
STOP with all the medications. Take him to a new doctor. Give him an oatmeal or Epsom salt bath....
good luck