Brief Answer:
Dont think it is related to surgery
Detailed Answer:
Hi and welcome.
If this was just partial colectomy without colostomy and with primary anastomosis then these diarrhea is not likely to be related with surgery. Only if more than 2/3 of colon is resected,then such difficulties may occur. Diarrhea may persist for few weeks after surgery but later it should be gone,especially after few months. So this is maybe related to anxiety,certain medications or diet. You should try with probiotics,easier god,boiled meat,fresh vegetables and fruit,avoid coffee,alcohol and carbonated drinks. Also,try to eat smaller meals but more often. if there won't be improvement,you should do colonoscopy and check your stool for parasitic infection. Wish you good health. Regards