amoxiciilin allergy or something else ???

my 4 1/2 yo daughter was put on amoxicillin for strep thraot, on day 9, she broke out in a rash..pediatrician said it was allergic reaction, stopped medication and  rash slowly went away over the course of the next few days.  My question is, ....exactly 1 week after amoxicillin was stopped, she started complaining of stomach pains and headache and has vomitted a couple of times. I don't think if a flu bug, (no fever, diarrhea, aches etc) think has been going on for over 1 week. She is acting normally, playing, etc just saying that her "tummy hurts" and or headache on and off all day for over week now. Any ideas ? Still an allergy ?  (also..2nd strep test was negative..so the infection was cleared up)

[Dr Rajput]

Hi, welcome to the forum, adverse cutaneous reactions to drugs are common encountered now a days esp. if the person has an allergic past history. It is quite evident that she is allergic to penicillins. Such allergy is seen in as high as 10% of patient ranging from mild rash to severe reactions and depends on the body's magnitude of sensitization to such drugs.

Patients who are allergic to penicillins should avoid all penicillins. Other groups of antibiotics that contain a beta-lactam structure similar to that of amoxicillin or ampicillin, include the cephalosporins, carbapenems, and monobactams.

As the offending drug is discontinued the allergic reaction to amoxicillin seems to be unlikely. It can cause delayed type of reaction and this can be possible. This type of reaction is known as serum sickness which can be associated with headache and gastro intestinal symptoms like vomiting and abdominal pain. But seems to be atypical.

She needs to undergo complete blood counts, C3 and C4 levels which will help to rule out the condition. Treatment includes anti histaminic and glucocorticoids against prescription. I suggest you to consult pediatrician. Take care and regards.