Thanks for writing your query.
A full clinical examination and some investigations are needed to reach to a diagnosis. There might be a possibility of hepatitis
or it could just be gastritis.
Following investigations may be helpful :-
1. Complete Blood Count
( CBC ).
2. Liver Function Test ( LFT ).
3. Urine examination.
4. Stool examination.
I would advise that he should be clinically examined by a medical professional.
An antacid like Omeprazole
40mg once a day before meals along with Domperidone
30mg can help in relief of the symptoms.
Further medical management can be planned after knowing the reports of the investigations.
I hope this is helpful to you.