Hello! Thank you for the query. Your symptoms can be related to the recent surgery only if there was any antibiotics treatment. Otherwise it is something else. Antibiotics treatment can cause gastrointestinal issues like diarrhea and abdominal pain. Its because antibiotic destroys good intestinal bacteria. This allow bad bacteria to grow. However most probable reason of your symptom are gallstones. Upper right abdominal pain radiating to the back, nausea, loss of appetite, loose stool are typical symptoms of this issue. I suggest you to have abdominal ultrasound and blood work (with liver tests) done. In case of gallstones, surgery is necessary. Please also start probiotic intake (should rebuild your good bacteria in the intestines) Hope this will help. Regards.