These are normally settled by anti allergic medicines but are temporary measures. Repeated anti allergics are not advisable.
As per Ayurveda principles, its 'Pittaj' jawar i.e. fever caused by vitiation of Pitta humor of Vata, Pitta, kafa).
Allergy,
urticaria,
low grade fever, acidity, headache are few symptoms.
If you agree a basic precipitant of Tinospora cordifolia herb called Giloy Satva or Guduchi Satva may be given to such children. You may get it world wide in the form of Guduchi capsules. Pour the contents and give to child twice a day with honey. Else get powder from India or online.
Amritarishta liquid is also made of Tinospora cordifolia as a main content which, if available, may also be added 1 tsp bd + equal water.
Results are slow but its 100% safe. About 4 to 8 weeks of treatment with it may ensure immunity against such manifestations for months ahead. It doesn't interact with any other drug too, so you can continue current medicine also (though no need).
For any other questions pl write direct.
Hope it helps.