Hi.
Thanks for your query.
Noted the history and understood your concerns.
Unable to eat or drink normally and have pain under left rib cage can be due to gastritis and colitis related problems.
Frequent urination, headache and fatigue indicate towards
urinary tract infection.
I would advise you the following in such a situation:
First of all send the sample of urine for routine, microscopy, culture and sensitivity before starting any antibiotic.
Send the blood and stool sample for tests.
Upper GI Endoscopy should be done to rule out any ulcer or cancer.
Ultrasonography of the whole abdomen to be followed by a CT scan should help more.
Clinical evaluation for probable diagnosis and correlating the reports of investigations should give a proper diagnosis.
Treatment may be in the form of an antibiotic for UTI, PPI like
Omeprazole,
Domperidone and antacids.
Rest of the treatment depends upon the diagnosis.