I am very sorry for the pain you are experiencing even after Appendicectomy surgery.
It may be Irritable Bowel Syndrome
.Please take a Pre and Probiotic capsule and a Proton pump inhibitor like Rabeprazole
But,you have to take Ultrasound abdomen and X ray abdomen to rule out Sub acute Intestinal obstruction
pathology and any pelvic lesion.
Hope you will be alright with above treatment.
Wish you speedy recovery