Hi,
Welcome to health care magic,
It would be slightly difficult to diagnose here in your case from only these symptoms like recurring headache and
stomach upset.
However,it could be related to
stomach infection or acute
gastroenteritis or might be due to some allergy as your doctor is suspecting but should be confirmed by appropriate investigations.
However,the chances of allergic could be there since you are responding to Z pack (
azithromycin 500) but must be confirmed by further tests.
Also,It would be better if you can tell me any other past history of any disease or medication or surgery.
So,you should go for routine blood investigations,ESR and urine with abdominal ultrasound and allergic testing for IgG,IgM.
Treatment is mainly based on the underlying cause. However you may take symptomatic treatment like,
1) Pain killers (if cause is not gastritis),
2) Antacids like ranitidine or
pantoprazole or rabeprazole,
3) Antihistamines like betahistine or cinnarizine.
If you still have not been relieved from the symptoms, then I would advise you to see your physician or allergic specialist for detailed history and thoroughly clinical examination to get the diagnosis first.
Thanks and Regards,