I had a surgery for appendix for 4 years now, but...

chronic pain at the surgical site what is the treatment ?
the treatment for such cases is by antiepiliptic drugs such as pregabalin , simple otc painkillers such as acetaminophin, NSAID drugs such as diclofen and doing relaxation sessions 
whjat might be the cause ?
the cause is what so called chronic pain syndrome and this syndrome cause is unknown but many patients have a chronic long lasting pain in the surgical sites that is physically un-explainable 
what are the signs and symptoms of chronic pain syndrome ?

• a pain in an old surgical site that ranges from tinkling pain that is barely felt to severe pain in the old surgical site and the doctor is unable to identefy any cause of the pain such as infection or hernia 

what are the diagnostic tests ?
the doctor will exam the patient clinically and take his past medical history and this is usually enough to make a diagnosis 
what is the advice ?
we advice you to practice yoga training and realxation trainings plus visiting a neurologist for the right diagnosis and the correct treament