I really think she his allergic to the antibiotic, you should consult a doctor, don't give it again before consulting a doctor, an allergic reaction can go bad to worse really quickly...
yes, it's possible she is allergic to some foods, but I would think it's more likely she's having an allergic reaction to the antibiotic. Even if she's had it before, she can still develop an allergy to it.
Some of the most common food allergies are:
peanuts or other nuts
eggs
milk
soy
strawberries
I would call her pediatrician and see if he suggests stopping the amoxicillin and if so, if there is something else he can prescribe for her.