Pain where? Lower or Upper ? Left or Right? Middle?
Did you do a blood test covering urea and electrolytes, Liver
function test, cancer markers and blood count?
Did you have an x ray done on your abdomen within the year of
symptom onset?
Did you go for colonoscopy?
Do you have a family history of any bowel problems?
Did you have diarrhea/vomiting?
I am hazarding a guess : it could be possibly an adhesion if it
feels like appendicitis to you - a post complication of abdominal
surgery i.e. your appendectomy. Ask your doctor to check it out and
do some tests to clear other probable causes.
For your reference if you want to know more :
http://www.emedicinehealth.com/adhesions_general_and_after_surgery/page3_em.htm#Adhesions%20Symptoms