hi i had gone through your query and understand your concerns. i would come up with two possibilities
1.the first one include,ALLERGY
;is the underlying cause for her sufferings.
-RESULT OF VACCINATION; sometimes vaccines may be the cause for development allergies
-general poor health are some possible causes.
2.second possibility is,ANEMIA;check their Hb% levels for confirmation.
i advise you taking Homeopathic
medicines gives safe and permanent cure for their complaints
consult your local homeopathic physician for correct diagnosis of the case and remedy to fit your kids complaints
I hope this is helpful for you, thank you