Hello and welcome to HCM,
A history of fever,
tiredness, mucus discharge from eyes which is greenish yellow,
vomiting and loss of appetite are suggestive of infection, most probably
conjunctival infection.
Conjunctivitis is characterized by infection and inflammation of conjunctiva which presents as redness of eyes, watering or mucus discharge from eyes and constitutional symptoms like fever, tiredness, loss of appetite etc.
Besides infection,
allergy can also present in similar way.
Presence of similar symptoms in younger grandson suggests an infective etiology or infectious cause for the symptoms.
I suggest you to consult an ophthalmologist for clinical assessment and definitive diagnosis.
Treatment can be planned once definitive diagnosis is made.
In the meanwhile, you can give anti-pyretic (fever controlling drug) to your grandsons.
Since, they are experiencing tiredness, rest is also required.
Thanks and take care
Dr Shailja Puri