if fever was the main symptom, the decreased platelet count was most likely
caused by a viral
infection (respiratory viral infection, common cold, enterovirus, etc.). if
it persists after the fever
resolves, it may satisfy the diagnosis of idiopathic thrombocytopenic
purpura. anyway, both
conditions have a very high chance of recovery without treatment.
avoid injury until the count recovers. but no need to worry too much since
the read was ~20,
~30. if it drops around or below 10, then there is increased risk of
internal bleeding.