Hi thanks for your question
The symptom you described, it looks like you have pharyngitis
,which is giving you ,headache and sore throat
Pain of pharyngitis is referred to your ear.
The second part of your question, you get diarrhea
whenever you eat.
This could be due same organism which is responsible for pharyngitis or it could be a separate disorder called as IBS
A course of antibiotic like leofloxicin will take care of your both infections and of course your pharyngitis additionally needs decongestant and antihistiminic .
Your IBS (irritable bowel syndrome
) needs treatment from a physician specialist.
Hope I answered your question